Multi-chamber deposition equipment for solid free form fabrication

ABSTRACT

Provided is a chamber system for solid free form fabrication, the chamber system having a deposition chamber, a service chamber and one or more loading/unloading chambers. The chamber system allows for a more efficient and cost effective process to service the deposition apparatus, load holding substrates, and unload workpieces without requiring having to adjust the atmosphere in the deposition chamber.

This patent application is a continuation of and claims priority toco-pending and co-owned U.S. patent application Ser. No. 16/927,164,filed Jul. 13, 2020, entitled “MULTI-CHAMBER DEPOSITION EQUIPMENT FORSOLID FREE FORM FABRICATION,” now U.S. Pat. No. 11,001,920, issued May11, 2021, which is a divisional of U.S. patent application Ser. No.15/206,163, filed Jul. 8, 2016, entitled MULTI-CHAMBER DEPOSITIONEQUIPMENT FOR SOLID FREE FORM FABRICATION, now U.S. Pat. No. 10,738,378,issued Aug. 11, 2020, both of which are hereby incorporated in theirentirety by reference herein.

FIELD OF THE INVENTION

The present invention relates to a method and arrangement formanufacturing objects by solid freeform fabrication, especially titaniumand titanium alloy objects.

BACKGROUND OF THE INVENTION

Metal parts having precise dimensional tolerances can be made oftitanium or titanium alloys are conventionally made by casting, forgingor machining from a billet. These techniques can require large leadtimes or high material use of the expensive titanium metal, or both, inthe fabrication of the metal part.

Fully dense physical objects may be made by a manufacturing technologyknown as rapid prototyping, rapid manufacturing, layered manufacturing,solid freeform fabrication (SFFF), additive fabrication, additivemanufacturing and 3D printing. This technique employs computer aideddesign (CAD) software to first construct a virtual model of the objectwhich is to be made, and then transform the virtual model into thinparallel slices or layers, usually horizontally oriented. The physicalobject can then be made by laying down successive layers of raw materialin the form of liquid, paste, powder or other layerable, spreadable orfluid form, such as melted metal, e.g., from a melted welding wire, orpreformed as sheet material resembling the shape of the virtual layersuntil the entire object is formed. The layers can be fused together toform a solid dense object.

Solid freeform fabrication is a flexible layered manufacturing techniqueallowing creation of objects of almost any shape at relatively fastproduction rates, typically varying from some minutes to several daysfor each object. The technique is thus suited for formation ofprototypes and small production series, and can be scaled up for massproduction.

The technique of layered manufacturing can be expanded to includedeposition of pieces of the construction material, that is, eachstructural layer of the virtual model of the object is divided into aset of pieces which when laid side by side form the layer. This allowsforming metallic objects by welding a wire onto a substrate insuccessive stripes forming each layer according to the virtual layeredmodel of the object, and repeating the process for each layer until theentire physical object is formed. The accuracy of the welding techniqueis usually too coarse to allow directly forming the object withacceptable dimensions. The formed object will thus usually be considereda green object or pre-form which needs to be machined to acceptabledimensional accuracy.

Taminger and Hafley (“Electron Beam Freeform Fabrication for CostEffective Near-Net Shape Manufacturing”, NATO/RTOAVT-139 Specialists'Meeting on Cost Effective Manufacture via Net Shape Processing(Amsterdam, the Netherlands, 2006) (NATO), pp. 9-25) discloses a methodand device for manufacturing structural metal parts directly fromcomputer aided design data combined with electron beam freeformfabrication (EBF). The structural part is built by welding on successivelayers of a metallic welding wire which is welded by the heat energyprovided by the electron beam. The EBF process involves melting a metalwire into a molten pool made and sustained by a focused electron beam ina high vacuum environment. The positioning of the electron beam andwelding wire is obtained by having the electron beam gun and theactuator supporting the substrate movably hinged along one or more axis(X, Y, Z, and rotation) and regulate the position of the electron beamgun and the support substrate by a four axis motion control system. Theprocess is reported to be nearly 100% efficient in material use and 95%effective in power usage. The method can be employed both for bulk metaldeposition and finer detailed depositions, and the method is claimed toobtain significant effect on lead time reduction and lower material andmachining costs as compared to the conventional approach of machiningthe metal parts. The electron beam technology has a disadvantage ofbeing dependent upon a high vacuum of 10⁻¹ Pa or less in the depositionchamber.

It is known (e.g., see Adams, U.S. Pat. Pub. No. 2010/0193480) to use aTIG-welding torch to build objects by SFFF, where successive layers ofmetallic feedstock material with low ductility are applied onto asubstrate. A plasma stream is created by energizing a flowing gas usingan arc electrode, the arc electrode having a variable magnitude currentsupplied thereto. The plasma stream is directed to a predeterminedtargeted region to preheat the predetermined targeted region prior todeposition. The current is adjusted and the feedstock material isintroduced into the plasma stream to deposit molten feedstock in thepredetermined targeted region. The current is adjusted and the moltenfeedstock is slowly cooled at an elevated temperature, typically abovethe brittle-to-ductile transition temperature of the feedstock material,in a cooling phase to minimize the occurrence of material stresses.

Withers et al. (U.S. Pat. Pub. No. 2006/185473) also describes using aTIG torch in place of the expensive laser traditionally used in a solidfreeform fabrication (SFFF) process with relatively low cost titaniumfeed material by combining the titanium feed and alloying components ina way that considerably reduces the cost of the raw materials. Witherset al. also describes using titanium sponge material mixed with alloyingelements formed into a wire where it can be used in an SFFF process incombination with a plasma welding torch or other high power energy beamsto produce near net shaped titanium components.

Abbott et al. (WO 2006/133034, 2006) describes a direct metal depositionprocess using a laser/arc hybrid process to manufacture complexthree-dimensional shapes comprising the steps of providing a substrateand depositing a first molten metal layer on the substrate from a metalfeedstock using laser radiation and an electric arc. The electric arc ingas metal arc welding can be provided by using the metal feedstock as anelectrode. Abbott et al. teaches that the use of laser radiation incombination with gas metal arc welding stabilizes the arc andpurportedly provides higher deposition rates. Abbott et al. utilizes aconsumable electrode guided by and exiting out of a wire guide. Themetal of the consumable electrode is melted at the end and the moltenmetal is deposited by positioning the end over the deposition point. Therequired heat for melting the consumable electrode is supplied by anelectric arc expanding between the tip of the electrode and theworkpiece/deposition substrate, and by a laser irradiating thedeposition area. Welding by melting a consumable electrode heated by anelectric arc is known as gas metal arc welding (GMAW), of which in thecase of using non-reactive gases to make the arc is also denoted asmetal inert gas welding (MIG-welding).

Titanium metal or titanium alloys heated above 400° C. may be subject tooxidation upon contact with oxygen. It is thus necessary to protect theweld and heated object which is being formed by layered manufactureagainst oxygen in the ambient atmosphere. WO 2009/068843 discloses aninert gas shield for welding which produces an even outflow ofprotecting inert gas. By placing the shield above the object which needsto be protected, the even flow of inert gas will displace ambientatmosphere without creating vortexes which may entrain ambient oxygencontaining gas. The shield can be formed as a hollow box of which theinert gas enters the interior and is allowed to escape the interior ofthe box through a set of narrow openings made in one wall of the box.Another solution to preventing oxidation of the titanium is to conductthe deposition process under vacuum.

For the above processes, the apparatus used often involves a singlechamber that is required to be evacuated or in which the atmosphere mustbe replaced every time it is loaded or unloaded and before thedeposition can begin. Similar types of single chamber apparatuses arealso used in coating and heating processes. Some examples include thosedisclosed in U.S. Pat. No. 4,328,257 disclosing a single chamberapparatus used for plasma coating. U.S. Patent Application PublicationNo. 2005/0173380 discloses a single vacuum chamber equipped with anelectron beam gun used to accomplish the deposition. U.S. PatentApplication Publication No. 2002/0139780 discloses a single chamberapparatus used for welding deposition.

A problem to be addressed is the speed of the deposition process and theexpenses resulting from the evacuation the chamber every time a newsubstrate is loaded or unloaded. Also, during plasma arc deposition, itis important to be able to control the temperature of chamber and of theequipment to prevent overheating. The temperature control must beachieved while still preventing the titanium metal or titanium alloysbeing heated above 400° C. from being subject to oxidation by preventingcontact with oxygen.

There exists a need, therefore, for a chamber deposition system thatprovides a more efficient and cost effective process that addresses oneor more of the above problems. This can further lead to increasedthroughput and yield of direct metal deposition formed products withoutthe risk of oxidation.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide an apparatus thatallows increased throughput and yield of products formed using directmetal deposition or SFFF without having to spend the time and expense toreplace the atmosphere in the deposition chamber every time service tothe deposition apparatus is necessary or every time a holding substrateis loaded or a workpiece unloaded from the deposition chamber.

Another objective of the invention is to provide an apparatus for rapidlayered manufacturing of objects in titanium or titanium alloys.

This invention addresses the needs for an improved, economical method ofperforming direct metal deposition. This invention further addresses theneed for a method of increasing throughput and yield of direct metaldeposition formed parts.

Provided herein is a chamber system for solid free form fabricationhaving one or more independently controlled loading/unloading chambers.The chamber system may include at least one independently controlleddeposition chamber, the deposition chamber including a depositionapparatus and an actuator that controls the position and movement of thebase material. One or more doors connect the deposition chamber witheach of one or more loading/unloading chambers. Optionally anindependently controlled service chamber can be connected to thedeposition chamber, the service chamber sized to house the depositionapparatus.

Each of the one or more loading/unloading chambers can include one ormore doors providing access to the loading/unloading chamber. A conveyoror like system can be located inside each loading/unloading chamber.Also, each loading/unloading chamber may be equipped with one or morevents. One or more vents can be located at an upper portion of theloading/unloading chamber and one or more vents can be located at abottom portion of the loading/unloading chamber. The one or more ventslocated at the upper portion can be operatively connected to a vacuumpump and to an air supply. The one or more vents located at the bottomportion can be operatively connected to a vacuum pump and to a source ofinert gas or inert gas mixture. Two loading/unloading chambers can havea wall shared between them. Also, each of the two loading/unloadingchambers can include a common wall with the deposition chamber.

The deposition chamber can also include one or more vents located at anupper portion of the deposition chamber and one or more vents located ata bottom portion of the deposition chamber. Like the loading/unloadingchambers, one or more vents located at the upper portion can beoperatively connected to a vacuum pump and to an air supply and one ormore vents located at the bottom portion can be operatively connected toa vacuum pump and to a source of inert gas or inert gas mixture. Thedeposition chamber can also include one or more viewing portals. Thedeposition chamber can include a recirculation system having a fan and aheat exchanger.

The service chamber can be aligned with the deposition chamber and thedeposition apparatus such that the deposition apparatus can move in andout of the service chamber without removing or bending the wire from thewire feeding system. The service chamber can also include one or morevents at an upper portion of the service chamber and one or more ventsat a bottom portion of the service chamber. The one or more ventslocated at the upper portion can be operatively connected to a vacuumpump and to an air supply, and the one or more vents located at thebottom portion can be operatively connected to a vacuum pump and to asource of inert gas or inert gas mixture. The service chamber caninclude an access portal. The service chamber also can include a set ofgloves.

Also provided herein are methods of operating a chamber system for SFFF.Methods of operating a chamber system for solid free form fabricationcan include independently replacing the atmosphere in the depositionchamber of a chamber system with an inert atmosphere; transferring afirst holding substrate on an actuator located inside the depositionchamber while maintaining the inert atmosphere in the depositionchamber; performing solid free form fabrication to form a firstworkpiece; and transferring the first workpiece out of the depositionchamber while maintaining the inert atmosphere in the depositionchamber. The chamber system can include at least two loading/unloadingchambers and a service chamber, each of the two loading/unloadingchambers and service chamber being in communication with the depositionchamber through one or more independent openings. One or more of thedeposition chamber, the at least two loading/unloading chambers andservice chamber have one or more doors to seal the one or more openings.Each of the deposition chamber, first and second loading/unloadingchambers and the service chamber can be controlled independently. Theone or more doors at each of the deposition chamber, first and secondloading/unloading chambers and the service chamber can be controlledusing one or more sensors. The solid free form fabrication can bestopped if one or more sensors detects that at least one door is notproperly sealed closed.

The methods can also include loading a first holding substrate on aconveyor located inside a first loading/unloading chambers; replacingthe atmosphere in the first loading/unloading chamber with the sameinert atmosphere as in the deposition chamber; and maintaining theatmosphere inside the first loading/unloading chamber during transfer ofthe holding substrate onto the actuator and during solid free formfabrication. The methods can also include loading a second holdingsubstrate onto a conveyor of a second loading/unloading chamber whilemaintaining the inert atmosphere in the first loading/unloading chamber;replacing the atmosphere of the second loading/unloading chamber withthe same inert atmosphere as in the deposition chamber. The firstworkpiece can be unloading by transferring it out of the depositionchamber and into the first loading/unloading chamber while maintainingthe inert atmosphere in the first loading/unloading chamber; sealing thefirst loading/unloading chamber from the deposition chamber; replacingthe inert atmosphere in the first loading/unloading chamber with ambientair; and unloading the workpiece from the loading/unloading chamber.After sealing the first loading/unloading chamber from the depositionchamber, a second holding substrate can be transferred from a secondloading/unloading chamber on the actuator while maintaining the inertatmosphere in the deposition chamber.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or can be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is an illustrative diagrammatic top view of a chamber systemaccording to an exemplary embodiment in which the deposition apparatusis located inside the deposition chamber.

FIG. 2 is an illustrative diagrammatic top view of a chamber systemaccording to an exemplary embodiment in which the deposition apparatusis located inside the service chamber.

FIG. 3 is a diagrammatic view of a recirculation system that may be usedto cool the atmosphere of a chamber, for example the deposition chamber.

FIG. 4 is a diagrammatic view of the arrangement of vents in anexemplary embodiment, such as in the deposition chamber.

FIGS. 5A and 5B are exemplary embodiments of a transferring mechanismbetween a loading/unloading chamber and the deposition chamber.

DETAILED DESCRIPTION

A. DEFINITIONS

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart to which the inventions belong. All patents, patent applications,published applications and publications, websites and other publishedmaterials referred to throughout the entire disclosure herein, unlessnoted otherwise, are incorporated by reference in their entirety. In theevent that there are a plurality of definitions for terms herein, thosein this section prevail. Where reference is made to a URL or other suchidentifier or address, it is understood that such identifiers can changeand particular information on the internet can come and go, butequivalent information can be found by searching the internet. Referencethereto evidences the availability and public dissemination of suchinformation.

As used herein, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise.

As used herein, the terms first, second, third, etc. may be used hereinto describe various elements, components, regions, layers and/orsections, these elements, components, regions, layers and/or sectionsshould not be limited by these terms. These terms may be only used todistinguish one element, component, region, layer or section fromanother region, layer or section. Terms such as “first,” “second,” andother numerical terms when used herein do not imply a sequence or orderunless clearly indicated by the context. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the example embodiments.

As used herein, ranges and quantities can be expressed as “about” aparticular value or range. “About” also includes the exact amount. Hence“about 5 percent” means “about 5 percent” and also “5 percent.” “About”means within typical experimental error for the application or purposeintended.

As used herein, “optional” or “optionally” means that the subsequentlydescribed event or circumstance does or does not occur, and that thedescription includes instances where the event or circumstance occursand instances where it does not. For example, an optional component in asystem means that the component may be present or may not be present inthe system.

As used herein, a “combination” refers to any association between twoitems or among more than two items. The association can be spatial orrefer to the use of the two or more items for a common purpose.

As used herein, “solid free form fabrication” refers to an additiveprototyping and manufacturing process in which a three-dimensionalobject is formed by successively adding layers of material to form thefinal object.

As used herein, the term “workpiece” refers to a metal body producedusing solid free form fabrication.

As used herein, “SFFF” refers to solid free form fabrication.

As used herein, a “Plasma Arc Welding torch” or “PAW torch” refers to awelding torch that can be used in plasma arc welding. The torch isdesigned so that a gas can be heated to a high temperature to formplasma and becomes electrically conductive, the plasma then transfers anelectric arc to a base material, and the intense heat of the arc canmelt metal and/or fuse two pieces of metal together. A PAW torch caninclude a nozzle for constricting the arc thereby increasing the powerdensity of the arc. The plasma gas typically is argon. Plasma gas can befed along an electrode and ionized and accelerated in the vicinity of acathode. The arc can be directed towards the base material and is morestable than a free burning arc (such as in a TIG torch). The PAW torchalso typically has an outer nozzle for providing a shielding gas. Theshielding gas can be argon, helium or combinations thereof, and theshielding gas assists minimizing oxidation of the molten metal. Currenttypically is up to 400 A, and voltage typically is in the range of about25-35 V (but can be up to about 14 kW). PAW torches include plasmatransferred arc torches.

The term “plasma transferred arc torch” or “PTA torch” as usedinterchangeably herein refers to any device able to heat and excite astream of inert gas to plasma by an electric arc discharge and thentransfer the flow of plasma gas including the electric arc out throughan orifice (such as a nozzle) to form a constricted plume that extendsout of the orifice and transfers the intense heat of the arc to a targetregion. In exemplary embodiments a PTA torch can be operated witheffects of 5-6 kW or higher.

The term “wire feed” as used herein refers to the wire being fed to thedeposition apparatus that melts the wire feed during solid free formfabrication. The term “wire feed material” as used herein refers to thematerial that makes up the wire feed and can be any known or conceivablemetal or metal alloy which can be formed into a wire and employed in asolid freeform fabrication process to form a three-dimensional object.Examples of suitable materials include, but are not limited to: titaniumand titanium alloys such as i.e. Ti-6Al-4V alloys, nickel or nickelalloys.

The term “holding substrate” as used herein refers to the targetsubstrate that is first loaded into the chambers upon which additionalmaterial, the same or different from that of the holding substrate, isdeposited using the technique of SFFF of solid free form fabrication toform a workpiece. In exemplary embodiments, the holding substrate is aflat sheet. In alternative embodiments, the holding substrate may be aforged part. In alternative embodiments, the holding substrate may be anobject upon which additional material is to be deposited. In exemplaryembodiments, the holding substrate can become part of the workpiece. Thematerial for the holding substrate can be a metal or a metal alloy. Inexemplary embodiments, the holding substrate is made of the same metalas the wire feed material.

The term “base material” as used herein refers to the target material.This will be the holding substrate when depositing the first layer ofmaterial. When one or more layers of material have been depositedhorizontally onto the holding substrate, the base material will be theupper layer of deposited metallic material that is to have deposited anew layer of metallic material. The base material and the depositedmaterial may be metals or metal alloys. In exemplary embodiments, thebase material is the same as the wire feed material.

The term “deposition apparatus” as used herein refers to any system thatcan be used for solid free form fabrication. Exemplary embodiments ofsolid free form systems include those using plasma arc (PAW), includingplasma transferred arc (PTA), laser sintering, electron beam, or anycombination thereof as a heat source for welding. In exemplaryembodiments the deposition apparatus includes one or more torches suchas PAW torch, laser torch or electron beam gun or torch. In exemplaryembodiments the deposition apparatus includes one or more transferredplasma arc torches. A PAW torch can be of any configuration capable ofcreating an electric arc to heat and melt the consumable electrode, suchas a metal wire, such as gas metal arc welding (GMAW) torch or atungsten inert gas (TIG) torch, particularly using inert or nobel gasesto make the arc. The metal wire is used as a consumable electrode and ismelted in the plasma produced by the torch using an electric arc, andthe melting consumable electrode is deposited onto the surface of orinto a molten pool on the base material to add to, and to form, the nearnet shape metal bodies or workpieces. Laser devices can generate a laserbeam having sufficient thermal energy to melt the metal wire onto a basematerial. Examples of suitable laser devices include a neodymium-dopedyttrium aluminum garnet (Nd:YAG) laser, a CO₂ laser, a CO laser, aytterbium fiber coupled diode laser, a Nd:glass laser, a neodymium-dopedyttrium orthovanadate (Nd:YVO) laser, a Cr:ruby laser, a diode laser, adiode pumped laser, an excimer laser, a gas laser, a semiconductorlaser, a solid-state laser, a dye laser, an X-ray laser, a free-electronlaser, an ion laser, a gas mixture laser, a chemical laser, andcombinations thereof. Preferred are Nd:YAG lasers and CO₂ lasers.Electron beam devices can be used for heating and melting a metal wireonto a base material. The electron beam device can be arranged anddisposed to direct an electron beam on the tip (distal end) of a metalwire positioned above the base material, so that the thermal energyproduced by the electron beam of the electron beam device melts the endof the wire, forming droplets of molten metal wire that drop onto thebase material beneath the end of the metal wire. The electron beamdevice can have a variable power output that can be adjusted to providea substantially constant power or energy amount to the metal wire in anamount that provides substantially constant melting rate of the metalwire. Electron beam guns are commercially available and described in theart. The electron beam gun can be selected so that it containselectromagnetic coils to modulate the electron beam. The electron beamgun can provide energy in the form of a concentrated stream of electronsaccelerated towards the metal wire. The electrons can be acceleratedusing a high voltage potential (e.g., greater than about 15 kV, such asin the range of from about 15 kV to about 150 kV) alone or incombination with magnetic fields. The electrons may be generated withinthe electron beam gun using one or more heated filaments. The outputpower of the electron beam gun typically can be controlled by regulatingthe flow of electrons to the work piece. For example, a beam power of upto about 30 kW can be used, but generally is within the range of fromabout 2.5 kW to about 10 kW, or from about 3 kW to about 6 kW. The beamcurrent generally is greater than about 100 milliamps, and can be in therange of from about 100 milliamps to about 600 milliamps. The beam poweris variable, and is generated by using an input voltage in the range offrom about 100 V to about 500 V. An exemplary input voltage is about 110V.

The term “computer assisted design model” or “CAD-model” as usedinterchangeably herein refers to any known or conceivable virtualthree-dimensional representation of the object that is to be formedwhich can be employed in the control system of the arrangement accordingto the second aspect of the invention: to regulate the position andmovement of the holding substrate and to operate the welding torch withintegrated wire feeder such that a physical object is built by fusingsuccessive deposits of the metallic material onto the holding substratein a pattern which results in building a physical object according tothe virtual three-dimensional model of the object. This may, forinstance, be obtained by forming a virtual vectorized layered model ofthe three-dimensional model by first dividing the virtualthree-dimensional model into a set of virtual parallel layers and thendividing each of the parallel layers into a set of virtual quasione-dimensional pieces. Then, the physical object can be formed byengaging the control system to deposit and fuse a series of quasione-dimensional pieces (droplets) of the metallic material feed onto thesupporting substrate in a pattern according to the first layer of thevirtual vectorized layered model of the object. The metallic materialfeed also can be deposited as a continuous supply of droplets, which canform a string or stream of metallic material. Then, repeating thesequence for the second layer of the object by depositing and fusing aseries of quasi one-dimensional pieces of the weldable material onto theprevious deposited layer in a pattern according to the second layer ofthe virtual vectorized layered model of the object. Repetition continuesduring the deposition and fusing process layer by layer for eachsuccessive layer of the virtual vectorized layered model of the objectuntil the entire object is formed.

However, the invention is not tied to any specific CAD-model and/orcomputer software for running the control system of the arrangementaccording to the invention, and nor is the invention tied to anyspecific type of control system. Any known or conceivable control system(CAD-model, computer-aided manufacture (CAM) system or software,computer software, computer hardware and actuators etc.) able to buildmetallic three-dimensional objects by solid freeform fabrication may beemployed. In exemplary embodiments, the control system can be adjustedto separately operate a first torch to preheat the base material and asecond torch to melt the feed wire of metallic material into the moltenpool. The first torch can provide sufficient energy to preheat the basematerial so that it is receptive to molten drops of melted metal wire,i.e. melted metallic material, at the position at which the meltedmetallic material is to be deposited. Preheating the base material canensure adequate melt-in to the base material by the metallic materialprovided by the metal droplet of the melted metal wire. The first torchpromotes fusion between the base material and the melted metallicmaterial by deepening the melt-in in the base material. In someembodiments, the preheating does not melt the base material. Inalternative embodiments, at least a portion of the base material ismelted by the first to make the base material more receptive. In someembodiments, sufficient heat is applied by the first torch to form amolten pool in the base material at the position at which the metallicmaterial is to be deposited.

B. MULTI-CHAMBER ASSEMBLY

Exemplary embodiments are described below in conjunction with theaccompanying figures. The following description is only illustrative andshould not be viewed as limiting.

FIG. 1 shows a diagram of an exemplary chamber system 100 having fourchambers 110, 120, 130, and 140. The four chambers can be connected toeach other. For purposes of this descriptions chambers 110 and 120 willbe referred to as the loading/unloading chambers, chamber 130 will bereferred to as the deposition chamber and chamber 140 will be referredto as the service chamber.

As their respective names implies, loading/unloading chambers 110 and120 can be used to load holding substrates to be used to form theobjects by solid free form fabrication and to unload formed workpieces.Likewise, deposition chamber 130 is a chamber in which the solid freeform fabrication process occurs. In exemplary embodiments the solid freeform fabrication is performed using plasma transferred arc torches. Inan exemplary embodiment the deposition apparatus is a wire feddeposition apparatus that employs two plasma transferred arc torches,one to form a molten pool in a base material into which melted metalfrom the wire feed drops, and the second torch to melt the wire feedmetal. In exemplary embodiments the wire feed material and the basematerial are the same. In exemplary embodiments the wire feed materialand base material are the metals or metal alloys. In exemplaryembodiments they are the same metal or metal alloy. Exemplary metals ormetal alloys for the wire feed material and base material are titanium,titanium alloys, nickel, or nickel alloys. Other metals or metal alloyscan also be used. Service chamber 140 can be a chamber dedicated tomaintenance work on the deposition apparatus.

Although the illustrative embodiments will be described as having fourchambers, it should be understood that loading/unloading chambers 110and 120 could be replaced by a single loading/unloading chamber.Alternatively, more than two loading/unloading chambers could beemployed and similarly connected to the deposition chamber. Moreover, itshould also be understood that an embodiment of the invention mayexclude service chamber 140.

Each chamber of chamber system 100 can be sealed off and independentlycontrolled. Each chamber can be sealed off from other chambers connectedthereto. Each chamber can also be sealed off from the outsideatmosphere. Each chamber can be separated from other chambers or fromthe outside atmosphere by using one or more swinging or sliding sealingdoors. In exemplary embodiments, a door may be made of the same materialas the chamber. In alternative embodiments each door may be made of asealing material. In exemplary embodiments, independent of the materialthe door is made of, each door may be equipped with a sealing member.The sealing member can be a ring, membrane or gasket. The sealingmaterial used for the sealing member or chamber door should be able toprovide a gas impermeable seal. In exemplary embodiments the sealingmaterial is any high vacuum sealing material. In exemplary embodiments,the sealing material can be polyurethane. In alternative embodiments thesealing material can be any one of nitrile rubber, fluorocarbon,silicone, fluorosilicone, or a perfluorinated elastomer. In exemplaryembodiments, more than one sealing material can be used for each sealingmember or chamber door. In yet alternative embodiments, each door can beequipped with more than one sealing member. For example two or threesealing members can be placed on the door to improve gas impermeability.

The atmosphere in each chamber can be independently evacuated. In someembodiments each chamber independently can be evacuated and replacedwith an atmosphere free of oxygen. In some embodiments each chamberindependently can be evacuated and then filled with an inert gas or gasmixture. Each chamber can be equipped with an individual flow controllerthat can measure and control the flow of gas into the chamber, such as amass flow controller or volumetric flow controller. Also, thetemperature in each chamber can be independently monitored, controlledand maintained. The pressure in each chamber may also be independentlymonitored, controlled and maintained. In embodiments in which a chamberis filled with an inert gas, such as argon, the pressure of that chamberis preferably maintained above atmospheric pressure. In exemplaryembodiments, the pressure of a chamber filled with an inert gas is keptat about 1 to 6 millibars above atmospheric pressure. Maintaining thepressure of a chamber above atmospheric pressure will assist inpreventing oxygen or other gases from outside the chamber from leakinginto the chamber. Any inert gas may be used to form an inert atmosphere.In exemplary embodiments the inert gas used is heavier than air. Anexemplary inert gas is argon. Other inert gases may also be used, aloneof in combination. In some embodiments, a gas mixture can be usedinstead of a single gas. For example, a mixture of argon with any ofhelium, neon, xenon or krypton can be used. Other possible gases thatcan be used alone or in a mixture include xenon and krypton.

For purposes of this specification the terms “heavy” or “heavier”referring to a gas, gas mixture or atmosphere and the terms “light” or“lighter” also referring to a gas, gas mixture or atmosphere are used todistinguish between any two types of atmospheres that can be used in thechambers described herein. As exemplified above, a heavy or heavier gasis argon or argon-helium mixture when compared to a lighter atmospheresuch as air. However, this pairing is only exemplary and should not beviewed as limiting. Also, while herein the vents are described in termsof heavy gas vents and light gas vents, it should be understood that twoatmospheres that are equal or very close in weight could also be used inwhich case any vent can be used for injecting or evacuating eitheratmosphere.

In exemplary embodiments, when not filled with an inert gas or duringthe process of filling a chamber with an inert gas, or during theprocess of evacuating a chamber of an inert gas, the chamber can bemaintained at atmospheric pressure. In alternative embodiments, when notfilled with an inert gas, a chamber may be maintained at vacuumconditions. Also, when filling a chamber with an inert gas or whenevacuating a chamber of an inert gas, the pressure in that chamber canbe either above or below atmospheric pressure.

Each chamber in chamber system 100 can be made of any suitable materialthat can withstand the pressure and temperature conditions of thechamber. For example, the material used to form the deposition chamber130 should withstand the pressure and temperature conditions of thesolid free form fabrication process carried out in that chamber. Inexemplary embodiments, the chambers are made of a metal. For example,the chambers can be made of aluminum metal or an aluminum alloy. In analternative embodiment the chambers can be made of steel. Any steel canbe used. Exemplary steels include low carbon steel, low alloy steel,high carbon steel, stainless steel, 300 series stainless steel, 400series stainless steel, austenitic stainless steels, high Cr ferriticsteels and Cr—Mo steels. In yet alternative embodiments, the chamberscan be made of a combination of metals. The metal walls can be properlygrounded to reduce the risk of generation of static discharges, or tominimize the risk of shock in case of any equipment malfunction.

In preferred embodiments, the chambers are maintained at or just aboveatmospheric pressure, thus a suitable material can include a materialthat is able to at least maintain physical integrity at least atatmospheric pressure or at a pressure that is from about 1-20 millibarsabove atmospheric pressure, or from about 1-10 millibars aboveatmospheric pressure, or about 2-8 millibars above atmospheric pressure.Preferably the material used for the chambers will also be able tomaintain physical integrity below atmospheric pressure, such as under avacuum. In such embodiments the material used should be able to maintainphysical integrity at a pressure that is below atmospheric pressure,particularly under the vacuum conditions used.

Any chamber of chamber system 100 can also be equipped with one or moreviewing portals so as to allow an operator to view the inside operation.In exemplary embodiments the viewing portals can be windows. Thedescription herein will refer to the viewing portals as windows,however, this should not be viewed as limiting as any type of viewingportal can be implemented herein. In exemplary embodiments, depositionchamber 130 may have a large window on at least one side so as to allowan operator to view the on-going fabrication process. Also, in apreferred embodiment service chamber 140 can also be equipped with atleast one large window to allow an operator to view the depositionapparatus 150 when inside service chamber 140. The one or more windowscan be made of any suitable transparent material that can also withstandthe pressure and temperature conditions of the chamber. For example, thematerial used to form the window in deposition chamber 130 shouldwithstand the pressure and temperature conditions of the solid free formfabrication process carried out in that chamber. In exemplaryembodiments, the material used for the windows in any one or morechambers is an acrylic material. In exemplary embodiments, the windowsare made of poly(methyl methacrylate). Alternatively, the windowmaterial can be a glass. In exemplary embodiments, the windows are madeof soda-lime-silicate glass. The glass can be coated with one or moretransparent metal oxide layers that can reflect selected wavelengths ofelectromagnetic radiation. In some embodiments, the glass can reflectinfrared electromagnetic radiation. In some embodiments, the glass canreflect ultraviolet electromagnetic radiation. The glass can be presentin a single layer, or a plurality of layers of glass can be used. Insome embodiments, at least two glass layers are present, separated by aspace. The space between the two layers of glass can be filled with aninert gas. In some embodiments, the space between the two layers ofglass is filled with argon. This configuration can block up to about 85%ultraviolet radiation from being transmitted through the window. In someembodiments, at least two glass layers are present, and an interlayer ofpolymer film present between the two glass layers, forming a laminatedglass. The polymer film can be of any polymeric material, such aspolyvinylbutyral (PVB), ethylene vinyl acetate (EVA). The laminatedglass can block nearly 100% ultraviolet radiation from being transmittedthrough the window.

Alternatively, the window material can be a thermoplastic polymer. Forexample, the material may be a polycarbonate, acrylic or polyethyleneterephthalate. The thermoplastic can be present as a single layer, ortwo or more sheets can be fabricated to include a space between thesheets, which optionally can be filled with argon, or a laminatedplastic window can be prepared by including an interlayer of polymerfilm between two sheets of thermoplastic polymer. The material used forthe one or more windows of one chamber can be the same or different fromthe material used for the one or more windows of any other chamber.Also, different windows of one chamber can be made of the same ordifferent materials.

In exemplary embodiments one or more chambers can be equipped with oneor more viewing devices. Exemplary viewing devices can be video cameras.The video captured by the one or more cameras can be recorded. The videocan also be streamed live. Video screens playing the video, live orrecorded mode, can be provided on the outside of the respective chamberfrom which the video was captured. The video can be viewed on a monitorproximate to the chamber from which the video was captured. The videocan be viewed on a monitor located at a remote location from the chamberin which the video was captured. Any combination of viewing videosarrangements described above can also be used.

Each chamber can also be equipped with one or more light emittingelements as sources of visible light to illuminate the chamber. Thesecan provide lighting inside the one or more chambers so as to providefor better visibility. A uniform brightness level in the chamber can beobtained by positioning light emitting elements symmetrically around thechamber. The one or more light emitting elements can be any suitablelight emitting device. For example, the light emitting element caninclude light fixtures. Additional examples can include light emittingdiode devices, neon lights, incandescent or fluorescent light bulbs, orany combination thereof. The brightness of the light emitting elementscan be adjustable. Appropriate protective covers of suitable materialstransparent to light can be provided to protect the light emittingelement from the conditions of the chamber in which the light emittingelement is located. In exemplary embodiments each chamber of chambersystem 100 includes at least a light emitting element. In exemplaryembodiments deposition chamber 130 includes one or more light emittingelements. In an exemplary embodiments service chamber 140 includes oneor more light emitting elements. In exemplary embodiments one or more ofloading/unloading chambers 110 and 120 each include one or more lightemitting elements. Any combination of these lighting arrangements canalso be implemented for chamber system 100. The light emitting elementsof each chamber can be independently controlled. Alternatively, alllight emitting elements can be connectedly controlled so that they canbe turned on and off at the same time. Alternatively, the light emittingelements of two or more chambers of chamber system 100 can be controlledsimultaneously. The lighting controls can be one or more manual orcomputerized control systems or a combination of both.

Each chamber can also be equipped with an oxygen detector or oxygenmonitoring device. In exemplary embodiments, the oxygen detector ormonitoring device can be used to check the amount of oxygen in thechamber when operated under inert atmosphere. As discussed earlier,during deposition, the metals can be heated to high temperaturesrendering them prone to oxidation. For example, titanium at atemperature of 400° C. or higher will typically oxidize in the presenceof oxygen. To prevent oxidation it is advantageous to maintain anatmosphere that is free of oxygen or alternatively an atmosphere thathas a very low oxygen content. In exemplary embodiments, when operatedin an inert atmosphere, the deposition chamber is maintained at apressure of about 10⁵ Pa with an oxygen content of less than 100 ppm,generally in a range of from about 0 to about 100 ppm, or in a range ofabout 0 to about 50 ppm. In alternative embodiments, the oxygen contentof the deposition chamber under similar conditions may be maintainedfrom about 0 to about 25 ppm or from about 0 to about 20 ppm.

In exemplary embodiments, the oxygen content and other atmosphericconditions including pressure of any other chamber within chamber system100 is similar to or lower than the oxygen content of the depositionchamber at least when such chambers are placed in atmosphericcommunication with deposition chamber if it is desired to maintain thedeposition chamber in an inert atmosphere. Likewise, in exemplaryembodiments in which the deposition chamber is maintained under vacuum,the other chambers of chamber system 100 are also under similar vacuumconditions at least when in atmospheric communication with thedeposition chamber. In exemplary embodiments where the depositionchamber contains air, the other chambers may also contain air at leastwhen in atmospheric communication with the deposition chamber. Bymaintaining the same or similar type of atmospheric conditions betweenchambers when in atmospheric communication with each other, it ispossible to better maintain and control the desired conditions withinthem. This can be especially important for the deposition chamberbecause it can help avoid unwanted introduction of impurities oroxidation during the manufacturing process that occurs in the depositionchamber.

In exemplary embodiments, the humidity level within the chamber iscontrolled. The humidity level is maintained at reduced levels to reducehydrogen content in the chamber. For example, when the metal wire is orcontains titanium, too high a hydrogen content within the chamber canmake the deposited titanium brittle. In exemplary embodiments, thehumidity level within any of the chambers within chamber system 100 canbe reduced to a level less than 250 ppm or less than 200 ppm. Inexemplary embodiments, the humidity level of the chambers connected tothe deposition chamber is similar to or lower than the humidity level ofthe deposition chamber, at least when such chambers are placed inatmospheric communication with the deposition chamber if it is desiredto maintain the reduced humidity level within the deposition chamber.

Although each chamber can be operated independently, it should beunderstood that in exemplary embodiments the same equipment can be usedto affect more than one chamber. For example, in an exemplary embodimenta single vacuum pump may be employed to create a vacuum in two or morechambers. In an exemplary embodiment a single vacuum pump is connectedto all four chambers by a common ventilation system. In suchembodiments, the vacuum can be used to evacuate the atmosphere in eachchamber independently by using a system of valves that separatelyconnects the ventilation system to each chamber. Thus, by independentlyopening and closing each valve, the vacuum can be applied to any one ormore chambers either simultaneously or at different times. Also,different vents of a chamber can be connected to a vacuum eithersimultaneously or at different times by controlling a set of valves.Likewise, in exemplary embodiments, a single supply system of inert gascan be connected to two or more chambers by way of independentlycontrolled valves. Thus, by operating each valve independently, inertgas can be provided to each chamber either simultaneously as the otherone or more other chambers or at different times.

The system can be configured so that the valves can permit or preventatmospheric communication between chambers. For example, a first chambercan be isolated from a second chamber so that the first chamber cancontinue to contain an inert or nobel gas, such as argon, while thesecond chamber is evacuated. A similar system can be used to supply airor other gas. Supply of inert gas or a gas mixture, air or otheratmosphere can be performed by any one or more vents in each chamberthrough the control of valves. Alternatively, each chamber can beequipped with its own independent vacuum pump. Also, each chamber can beequipped with its own independent source of air, inert gas or gasmixture, or other gas as desired.

Controls for the chamber system 100 and the operation of each chambercan be housed in a control system. A control system can be manuallyoperated. For example, a manually operated control system may includemanually operated valves, gears, switches or similar devices. In thealternative, a control system can be automated. For example, the controlsystem can consist of a computerized control system. In yet alternativeembodiments, a control system can be a combination of manual andcomputer controls. Each chamber can be equipped with its own individualcontrol system. In an exemplary embodiment, a single control system canindependently control each chamber. An exemplary control system caninclude an industrial computer, which can be configured to contain acentral processing unit for executing a user program, one or more powersupplies, and signal modules as inputs and/or outputs. The controlsystem can include a CPU display and integrated shielding of analogsignals. Such control systems can be designed by the skilled artisan. Anexemplary commercially available system is the SIMATIC-S7-1500 fromSiemens AG (Munich, Germany). A separate control system can be used toregulate the equipment located inside the chambers. For example, aseparate control system can be used to regulate the actuator 131. Anexemplary commercially available system is the IndraMotion MTX systemavailable from Bosch Rexroth AG (Lohr am Main, Germany). A separatecontrol system can be used to control the welding equipment. Anexemplary commercially available system is the SIGMATEK C-IPC compactindustrial computer system available from SIGMATEK GmbH & Co. KG(Lamprechtshausen, Austria). Each chamber can have its own separatecontrol system for the equipment used therein. Alternatively, eachequipment may have an associated separate control system. A centralcontrol system can also be used to control the equipment located insidethe chambers. Alternatively, central control system can be incommunication with each separate control system.

LOADING/UNLOADING CHAMBERS

In an exemplary and illustrative embodiment, chamber system 100 caninclude two loading/unloading chambers 110 and 120. In alternativeembodiments, chamber system 100 can include only one loading/unloadingchamber. In yet alternative embodiments, chamber system 100 can includemore than two loading/unloading chambers. The operation of aloading/unloading chamber does not change and is independent of how manyof these chambers are included in chamber system 100. In theillustrative example shown in FIG. 1 , loading/unloading chambers 110and 120 can be arranged such that they have a wall in common.

An advantage of having at least two loading/unloading chambers is thedecrease in production cycle-time that is a result of the ability tomore quickly load and unload holding substrates and workpieces. Forexample, in embodiments in which an inert atmosphere is maintained inthe deposition chamber 130, the loading/unloading chamber must also havean inert atmosphere when in atmospheric communication with depositionchamber 130. However, loading a holding substrate into theloading/unloading chamber exposes the loading/unloading chamber to theoutside atmosphere. Thus, in order to have a loading/unloading chamberat inert gas atmosphere, the air in the loading/unloading chamber mustbe flushed out and replaced with inert gas before the door connectingthe loading/unloading chamber to the deposition chamber can be opened sothat no air is introduced in the inert atmosphere of the depositionchamber. This is likewise the case if the deposition chamber wereoperated under vacuum conditions or in any atmosphere other than air. Byhaving at least two loading/unloading chambers, it is possible to haveone loading/unloading chamber ready to receive a workpiece from thedeposition chamber, while the other loading/unloading chamber is readyto load the next holding substrate.

Each loading/unloading chamber can be equipped with at least two doors.In exemplary embodiments, loading/unloading chamber 110 includes a door111 that provides access to chamber 110 from outside the chamber.Chamber 110 can also be equipped with a second door 112 that connectschamber 110 to deposition chamber 130. Likewise, loading/unloadingchamber 120 can be equipped with similar doors 121 and 122. As discussedearlier, each door 111, 112, 121 and 122 can either be made of sealingmaterial or include one or more sealing members such that each door isgas impermeable. Doors 111, 112, 121 and 122 can be sliding doors orswing doors. In exemplary embodiments doors 111, 112, 121 and 122 aresliding doors that slide side to side or top to bottom to open andclose. Doors 111, 112, 121 and 122 may also be equipped with hinges thatprovide pressure on the doors when closed to improve their seal and torelease the pressure when the doors are to be opened. In exemplaryembodiments doors 111, 112, 121 and 122 can be manually operated.Alternatively, doors 111, 112, 121 and 122 can be operated automaticallyor by the control system. In exemplary embodiments, doors 111, 112, 121and 122 can be operated both manually and automatically. Also, each door111, 112, 121, and 122 can be a set of two or more doors that can beoperated simultaneously or independently.

The service chamber and each loading/unloading chamber can be equippedwith its own independent ventilation system. For example, each ofchambers 110, 120 and 140 can be independently vented. Each of chambers110, 120 and 140 can independently be filled with an inert gas such asargon. Each of chambers 110, 120 and 140 can independently be filledwith air. The inlet flow to any of chambers 110, 120 and 140 can be inthe range of from about 100 to about 1500 liters/min. The flow into thechambers can be controlled by a mass flow controller. The pressurewithin a chamber is close-loop controlled by opening and closing anexhaust valve. For example, closing all of the vents connected to avacuum while opening at least one vent connected to an inert gas supplycan increase the pressure within the chamber. The length of timenecessary to replace an air atmosphere within a chamber with an inertgas to achieve a certain oxygen level varies according to the dimensionsof the chamber as well as the amount of equipment within the chamber,which displaces a certain volume that otherwise would need to beoccupied by the gas within the chamber.

Each of chambers 110, 120 and 140 can independently be kept under vacuumconditions. The atmosphere in each of chambers 110, 120 and 140 canindependently be evacuated. Vents used to evacuate the atmosphere ofchambers 110, 120 and 140 can operate at any suitable flow rate. Theflow rate may be defined by the by the capacity of the fan used. Forexample, evacuation vents can operate at 3000 to 6000 Sm³/hr. In anexemplary embodiment, the capacity of the fan used is 4500 Sm³/hr.Likewise, inlet vents injecting inert, nobel or other gas or air insidechambers 110, 120 and 140 can operate at any suitable flow rate. In someapplications, the maximum inlet flow to any one of chambers 110, 120 and140 is 1500 L/min. A mass flow controller can be used to regulate theinlet flow of inert gas or other gas or air into any one of thechambers. The inlet flow can be in a range of from about 10 to about1500 L/min, or from about 100 to 1500 L/min. The pressure within the anyone of the chambers can be a closed-loop controlled system, in which thepressure can be regulated by opening and closing an exhaust valve. Thesystem can include an idle mode in which the system is maintained at adesired pressure and oxygen level. During the idle mode, a low flow ofinert gas or other gas into any one of the chambers can be maintained,such as a flow in the range of about 10 L/min. to about 100 L/min., andcan be modified by adjusting the outlet valve to increase or decreaseflow through the exhaust valve. Inlet and outlet vents can also haveinterchangeable operability. Inlet vents can operate as outlet vents andoutlet vents can also operate as inlet vents. The vents can includesvalves to control the flow rate of gas through the vents, and therebyregulate the resulting pressure within a chamber. The chamber caninclude pressure monitors, and in response to a reading from a pressuremonitor, the valve of a vent connected to an inert gas source can beopened or closed to adjust the pressure within the chamber.

The temperature and pressure of each of chambers 110 and 120 can beindependently controlled and maintained. In exemplary embodiments inwhich an inert gas heavier than air is used as the atmosphere inside thechamber system 100, loading/unloading chambers 110 and 120 can includeone or more vents that introduce the inert gas or gas mixture located ata bottom portion of the chambers and one or more vents connected to avacuum to evacuate air or other light gasses at an upper portion of thechambers. In this manner the heavier inert gas is introduced from thebottom and the lighter atmosphere, for example air, is vented out fromthe upper portion of the chambers. Each vent can include a connection toa manifold that allows connection of the vent to several differentsources with different gases as well as to a vacuum source, the manifoldcontaining vales to regulate which source will be available to the ventat a given moment. This allows a more effective system to fully flushout and replace the atmosphere with an inert gas. Likewise, if theheavier inert gas or gas mixture is to be replaced with a lighteratmosphere such as air, the bottom vents can be used to evacuate theinert gas and the upper vents can be used to introduce the lighteratmosphere. In exemplary embodiments, one or more bottom vents can belocated in the floor. In exemplary embodiments, one or more bottom ventscan be located at the bottom of the chamber walls just above the floor.In yet alternative embodiments, one or more bottom vents can be locatedboth in the floor and at the bottom portion of the chamber walls. Inexemplary embodiments, one or more upper vents are located in thechamber ceiling. In exemplary embodiments, one or more upper vents arelocated at the upper portion of the chamber walls just below the chamberceiling. In exemplary embodiments, one or more upper vents are locatedboth in the ceiling and at the upper portion of the chamber walls justbelow the chamber ceiling. Each bottom and upper vent independently canbe equipped with a fan.

When operating one or more vents to evacuate a gas or atmosphere fromchambers 110 and 120 each vent can be connected to separate vacuumpumps. Alternatively, each vent can be connected by way of independentlycontrolled valves to a common vacuum pump used for all of chamber system100. Each vent can be connected with its own independently controlledvalve. Alternatively, two or more vents used to evacuate of chamber 110can be connected to vacuum via a common independently operated valve.Likewise two or more vents used to evacuate chamber 120 can be connectedto vacuum via a common independently operated valve. Alternatively, allupper vents of chamber 110 can be connected to vacuum via a first commonindependently operated valve and all bottom vents of chamber 110 can beconnected to vacuum via a second common independently operated valve.Top and bottom vents in chamber 120 can similarly be connected to vacuumas done in chamber 110.

The vents used to introduce an inert gas, gas mixture, air or otheratmosphere into chambers 110 and 120 can be similarly arranged as thevents used to evacuate chambers 110 and 120. For instance, each vent canbe connected to an independent source. Alternatively, two or more ventscan be connected to a common source. In this latter embodiment, eachvent can be independently controlled by an independently controlledvalve. Alternatively, two or more vents of chamber 110 can be connectedto a common, independently controlled valve. Likewise, two or more ventsof chamber 120 can be connected to a common, independently controlledvalve. Alternatively, all upper vents of chamber 110 can be connected toa common source via a first common independently operated valve and allbottom vents of chamber 110 can be connected to a common source via asecond common independently operated valve. Top and bottom vents inchamber 120 can similarly be connected to one or more sources as done inchamber 110.

Each loading/unloading chamber 110 and 120 can be equipped withtemperature control device. The temperature control device of each ofchambers 110 and 120 can be independently controlled. The temperaturecontrol device can include an electric heater, a gas heater, a heatexchanger, an electric cooling system, a refrigeration system, a chilleror a combination thereof. Each chamber 110 and 120 may also be equippedwith one or more thermometers, thermocouples or other temperaturesensing devices, or a combination thereof to determine the temperatureof the chamber. The temperature sensing devices and temperature controldevice can be connected to the respective control system that controlsthe chamber they affect.

Each loading/unloading chamber 110 and 120 can also be equipped with oneor more pressure gauges, vacuum gauges or combination thereof. Thegauges can be connected to the respective control system that controlsthe chamber they measure.

Each loading/unloading chamber 110 and 120 can each be respectivelyequipped with a transferring mechanism 113 and 123, each able to receivea holding substrate and transfer the holding substrate into thedeposition chamber 130. The transferring mechanism 113 and 123 can alsobe able to retrieve a workpiece from the deposition chamber 130 andtransfer it to another location, for example to the operator spaceoutside the chamber.

Any transferring mechanism that can handle the weight of the holdingsubstrate and workpiece and the atmosphere, temperature and pressure ofthe chamber can be used for transferring mechanism 113 and 123. Inexemplary embodiments, the transferring mechanism can be a conveyor. Inexemplary embodiments, the conveyor can comprise a conveyor belt, achain conveyor, or other mechanical conveyor system. The conveyor caninclude a set of gears and wheels that are able to support and transferthe holding substrate or workpiece. In exemplary embodiments, thetransferring mechanism 113 and 123 can also include a set of mechanicaland/or hydraulic arms that can assist in the transferring, lifting orpositioning of the holding substrate or workpiece. In exemplaryembodiments, the transferring mechanism 113 and 123 can further includea set of wheels that can extend to an actuator 131 inside depositionchamber 130. In exemplary embodiments, a pair of extendable arms withwheels are designed to extend to actuator 131. The wheels in theextendable arms can be designed to be positioned underneath the holdingsubstrate or workpiece and then lift the holding substrate or workpieceand position the same either onto actuator 131 or back onto transferringmechanism 113 or 123.

For example, as illustrated in FIGS. 5A and 5B, the transferringmechanism 113 can include a pair of parallel chain conveyors 171 and 172that can act as arms that can be fully retracted into loading/unloadingchamber 110 and extended out of into deposition chamber 130 to reachtracks 132 and 133. Tracks 132 and 133, which can be configured to moveorthogonally to each other, can position actuator 131 in front of door112. When actuator 131 is in position, the a pair of chain conveyors 171and 172 that make up transferring mechanism 113 are extended out ofchamber 110, with one chain conveyor on one side of the actuator 131 andthe other chain conveyor on the other side of actuator 131 as forexample illustrated in FIG. 5A. Activation of transferring mechanism 113moves the holding substrate out of chamber 110 and can position theholding substrate above actuator 131. Actuator 131 engages with theholding substrate, such as by elevating the holding substrate relativeto the transferring mechanism 113 so that the holding substrate nolonger is engaged with transferring mechanism 113. The now disengagedtransferring mechanism 113 is retractable into chamber 110 as forexample illustrated in FIG. 5B. With the transferring mechanism 113moved out of the way, tracks 132 and 133 can position the actuator 131with the attached holding substrate into proper position relative to thedeposition apparatus 150 to undergo free form fabrication. The holdingsubstrate, or base material can continued to be moved by actuator 131during the deposition process. Once the deposition is complete, theworkpiece can be transferred back into the loading/unloading chambers ina similar way as it was loading. For example, the actuator 131 carryingthe workpiece can position itself in front of the door to theloading/unloading chamber, and the transferring mechanism 113 can againextend arms 171 and 172 from the loading/unloading chamber into thedeposition chamber and lift the workpiece off the actuator 131. Thetransferring mechanism 113 can then carry the workpiece into theloading/unloading chamber by retracting into the loading/unloadingchamber while carrying the workpiece. In exemplary embodiments a set ofrollers or a similar supporting and transferring structure (not shown)may also be provided outside chambers 110 and 120 in proximity of doors111 and 121 to aid in the loading and unloading of holding substratesand workpieces.

In exemplary embodiments, loading/unloading chambers 110 and 120 areunder the same atmospheric conditions as deposition chamber 130 when incommunication with deposition chamber 130. Thus, for example, ifdeposition chamber 130 is operated under inert gas atmosphere,loading/unloading chambers 110 and 120 are also operated under inert gasatmosphere when in atmospheric communication with deposition chamber130. In such exemplary embodiments, the inert gas atmosphere may includeargon, or an argon-helium mixture.

Any one or more of the doors providing access to loading/unloadingchambers 110 and 120 can be equipped with one or more sensors able todetect when the given door is open or closed. The one or more sensorscan be connected to the control system controlling deposition apparatus150. In exemplary embodiments, if the any one of the one or more sensorsdetects that any one or more of the doors of loading/unloading chambers110 and 120 is opened when the one or more doors should be closed, or ifthe one or more doors are not properly sealed shut as they should be,the one or more sensor can communicate it to one or more control systemsof chamber system 100. The one or more control systems can send a signalto deposition apparatus 150 to stop the fabrication process if inprogress or to prevent it from starting. The one or more sensors canalso trigger an audible alarm, such as siren, warning voice and/orbeeping noise, visual alarm, such as a flashing light, blinking of lightemitting elements inside one or more chambers, screen warnings on theone or more control systems, or combination thereof.

DEPOSITION CHAMBER

In exemplary embodiments, chamber system 100 includes at least onedeposition chamber 130. Deposition chamber 130 can be large enough tohouse all the necessary equipment to produce the workpiece using SFFF.In exemplary embodiments, deposition chamber 130 is the largest of thechambers that make up chamber system 100. Deposition chamber 130 is achamber in which the solid free form fabrication is conducted.Deposition chamber 130 can be designed to withstand the conditions thatare required during solid free form fabrication. In exemplaryembodiments, the solid free form fabrication is performed using a plasmatransferred arc. Particularly, in exemplary embodiments, the solid freeform fabrication can be carried out using two plasma transferred arctorches. In alternative embodiments, the solid free form fabrication canuse electron beam deposition. Alternatively, the solid free formfabrication can use selective laser sintering. The deposition chambercan be designed and configured so that any solid free form fabricationmethod or any combination of multiple layer fabrication methods may beconducted inside deposition chamber 130. For illustrative purposes,deposition chamber 130 is described herein in conjunction with a plasmatransferred arc type solid free form fabrication method.

In illustrative embodiments, the solid free form fabrication method mayinvolve a movable deposition apparatus 150. The degree of movability ofthe deposition apparatus 150 can be designed as desired. In exemplaryembodiments, the deposition apparatus 150 is provided on a robotic,mechanical, and/or hydraulic arm like device that is able to move thedeposition apparatus in any direction during the fabrication process.For example, in a plasma transferred arc fabrication, one or more plasmatransferred arc torches may be connected to one or more mechanical armsthat can move the plasma transferred arc torches as necessary to formthe workpiece. Alternatively, the motion of the deposition apparatus 150may be limited to only one axis. In other embodiments, the motion of thedeposition apparatus 150 may be limited to two axis. For example, asillustrated in FIGS. 1 and 2, the motion of the deposition apparatus 150may be limited to forward and backward movements along the same line asthe wire feed 160. In the illustrated example, the deposition apparatus150 can be engaged with a track, rail or conveyor system. The track,rail or conveyor system may be located for example on the ceiling ofdeposition chamber 130. Alternatively the track, rail or conveyor systemmay be located along a wall of deposition chamber 130. Alternatively,the track, rail or conveyor system may be located on the floor ofdeposition chamber 130. In exemplary embodiments, deposition apparatus150 may be connected to more than one track, rail or conveyor system,and the tracks, rails or conveyor systems located on one or more of theceiling, walls and/or floor of chamber 130. In yet alternativeembodiments, deposition apparatus 150 can be fixed and not moveable, butrather it is the workpiece that moves. In yet alternative embodiments,deposition apparatus 150 is movable only in the vertical direction orZ-direction. In yet alternative embodiments the deposition apparatus 150can move in the vertical direction, i.e. up and down, as well as movefrom the deposition chamber to the service chamber via one or moretracks, rails and/or conveyor systems as described above.

Any combination of motors, gears, wheels, pulley systems, and conveyorscan be used to implement the movement of deposition apparatus 150. Anysuch motors, gears, wheels, pulley systems and conveyors can be providedon the deposition apparatus 150. Alternatively they can be providedinside or outside deposition chamber 130. In exemplary embodiments, someof the motors, gears, wheels, pulley systems, and conveyors are providedon deposition apparatus 150 and some are provided either inside oroutside of deposition chamber 130. The motion of deposition apparatus150 can be controlled using a control system associated with depositionchamber 130. Alternatively, control of motion of deposition apparatus150 can be accomplished through an independent control system. Thecontrol system for the motion of deposition apparatus 150 can be manual,automated or a combination thereof.

In exemplary embodiments, deposition chamber 130 also includes anactuator 131. Actuator 131 can be used to hold the holding substrate orbase material during fabrication of an object. Actuator 131 can also bedesigned to move the holding substrate, base material, or workpiece inmultiple directions. Alternatively, the motion of actuator 131 can bedesigned to stay in a fixed location. In exemplary embodiments actuator131 is able to move in multiple directions while deposition apparatus150 remains in a fixed location during fabrication. Alternatively,deposition apparatus 150 and actuator 131 both move during fabrication.In yet an alternative embodiment, deposition apparatus 150 moves duringfabrication while actuator 131 remains in a fixed position. By movingthe deposition apparatus 150 and/or the actuator 131 a depositionpattern can be defined to complete the 3-D object or workpiece bydepositing successive layers of metallic material obtained from meltingthe metal wire.

Actuator 131 can be provided on a track system that allows for movementof the actuator in any desired direction. The mechanism used to move theactuator should not be viewed as limiting. In exemplary embodimentsillustrated in FIGS. 1 and 2 , actuator 131 can be provided on a firsttrack 132 that is able to move actuator 131 along a first axis. Track132 can itself be provided on a second track 133 that is able to movetrack 132, and thus actuator 131, along a second axis. In a preferredembodiment the axis of motion of track 132 is perpendicular to the axisof motion of track 133. In the illustrated arrangement, any motion,including a 360° rotation, can be achieved for actuator 131. Actuator131 can also be equipped with a lifting or lowering arm or piston or asimilar device that can move actuator 131 in the vertical direction.Tracks 132 and 133, and actuator 131 can be formed of any material thatis suitable for the pressure, temperature, atmosphere, and for holdingthe holding substrate or workpiece during the solid free formfabrication. In exemplary embodiments, tracks 132 and 133 and actuator131 are made of the same material. In alternative embodiments actuator131 is made of a material that is different from that of tracks 132 and133. Alternatively, each of track 132 and 133, and actuator 131 are madeof a different material. Exemplary materials that can be used includemetals, such as aluminum, aluminum alloys and steel.

Also, any one or more of actuator 131, and tracks 132 and 133 can beequipped with a heating or cooling system. In exemplary embodiments, oneor more of actuator 131, and tracks 132 and 133 is equipped with a heatexchanger. In exemplary embodiments, one or more of actuator 131, andtracks 132 and 133 is equipped with a heater. In exemplary embodiments,one or more of actuator 131, and tracks 132 and 133 is equipped with aheat sink. In exemplary embodiments, one or more of actuator 131, andtracks 132 and 133 is equipped with a chiller or a cooling systeminvolving a cooling fluid. The cooling fluid may be air, an inert gas,or water or other suitable fluids. Examples of cooling fluids that areliquids include water, alkylene glycol (e.g., ethylene or propyleneglycol), mineral oil, silicone oil, or combinations thereof. In someapplications, the cooling fluid includes water and an alkylene glycol.The cooling fluid on the cold side of the heat exchanger can be selectedto be in a temperature range of from about 5° C. to about 25° C.

Tracks 132 and 133 may be operated by any combination of motors, gears,pulley system or like mechanism. The movement of actuator 131 can becontrolled by a control system. The control system can be manual orautomated. The control system for actuator 131 can be the same systemthat controls deposition chamber 130. Alternatively actuator 131 canhave its own independent control system.

The atmosphere, temperature and pressure of deposition chamber 130 canbe monitored, modified and controlled in the same manner as describedabove for loading/unloading chambers 110 and 120. For example,deposition chamber 130 may be equipped with one or more pressure gaugesto monitor the pressure within chamber 130. The pressure gauges can bein communication with a control system that controls chamber 130. Also,deposition chamber 130 can be equipped with temperature control devices.The temperature control devices can include an electric heater, a gasheater, a heat exchanger, chiller, an electric cooling system or acombination thereof. Deposition chamber 130 can be equipped with one ormore thermometers, thermocouples or other temperature sensing devices,or a combination thereof to determine the temperature of the chamber.The temperature sensing devices and temperature control devices can beconnected to a control system that controls deposition chamber 130.

Deposition chamber 130 can be equipped with its own independentventilation system. Deposition chamber 130 can independently be filledwith an inert gas such as argon. Deposition chamber 130 canindependently be filled with air. Deposition chamber 130 canindependently be kept under vacuum conditions. The atmosphere indeposition chamber 130 can independently be evacuated. The temperatureand pressure of deposition chamber 130 can be independently controlledand maintained. As illustrated in FIG. 4 , in exemplary embodiments inwhich an inert gas or gas mixture heavier than air is used as theatmosphere during the solid free form fabrication, deposition chamber130 can include one or more vacuum or inert gas vents 310 at a bottomportion the chamber and one or more vacuum or air or light gas vents 320at an upper portion of the chamber. In this manner the heavier inert gascan be inlet or evacuated from the bottom and the lighter atmosphere,for example air, can be inlet or evacuated from the upper portion of thechamber. This allows a more effective system to fully flush out andreplace the atmosphere. To further promote avoiding creating any deadpockets of air, the floor 330 of deposition chamber 130 may be curved.As illustrated in FIG. 4 , for example, floor 330 can have down slopingsides extending to each chamber wall. Alternatively, floor 330 may haveonly one or two down sloping sides.

Vents used to evacuate the atmosphere of deposition chamber 130 canoperate at any suitable flow rate depending on the capacity of the fanused. For example, evacuation vents can operate at 3000 to 6000 Sm³/hr.In an exemplary embodiment, the capacity of the fan used is 4500 Sm³/hr.Likewise, vents introduce inert or other gas or air inside depositionchamber 130 at any suitable flow rate. In some applications, the maximuminlet flow to the deposition chamber 130 is 1500 L/min. A mass flowcontroller can be used to regulate the inlet flow of inert gas or othergas or air into the chamber. The inlet flow can be in a range of fromabout 10 to about 1500 L/min, or from about 100 to 1500 L/min. Thepressure within the chamber can be a closed-loop controlled system, inwhich the pressure can be regulated by opening and closing an exhaustvalve. The system can include an idle mode in which the system ismaintained at a desired pressure and oxygen level. During the idle mode,a low flow of inert gas or other gas into the chamber can be maintained,such as a flow in the range of about 10 L/min. to about 100 L/min., andcan be modified by adjusting the outlet valve to increase or decreaseflow through the exhaust valve.

In exemplary embodiments, one or more vents 310 used to introduce orevacuate heavier gas or gas mixture atmosphere can be located in thefloor. As shown in FIG. 4 , in exemplary embodiments, one or more vents310 can be located at the bottom of the chamber walls just above thefloor. For example, vents 310 could be located at one or more corners ofdeposition chamber 130, just above where the down sloping side of floor330 meets the chamber walls. In yet alternative embodiments, one or morevents 310 can be located both in the floor and at the bottom portion ofthe chamber walls. Vents 310 can be equipped with fans. The vans can beselected (such as to have a desired speed (rpm) and air flow (m³/hr.)and can be positioned so that the operation of the fan minimizes theintroduction of any atmospheric turbulence inside the chamber due to theoperation of the fans.

In exemplary embodiments, one or more vents 320 used to introduce orevacuate a light gas atmosphere, such as air, are located in the chamberceiling. In exemplary embodiments, one or more vents 320 are located atthe upper portion of the chamber walls just below the chamber ceiling.In exemplary embodiments, one or more vents 320 are located both in theceiling and at the upper portion of the chamber walls just below thechamber ceiling. Vents 320 can be equipped with a fan.

The vents of deposition chamber 130 can be connected to separate vacuumpumps. Alternatively, the vents of deposition chamber 130 can beconnected by way of independently controlled valves to a single vacuumpump used for all of chamber system 100. Each vent can be connected tovacuum with its own independently controlled valve. Alternatively, twoor more vents of chamber 130 can be connected to vacuum by way of acommon independently operated valve. For example, all upper vents ofdeposition chamber 130 can be connected to vacuum by way of a firstcommon, independently operated valve, and all bottom vents of depositionchamber 130 can be connected to vacuum by way of a second common,independently operated valve. The pressure within the chamber can beregulated by opening or closing these valves. For example, by closingthe vents connects to a vacuum and opening the vents connected to aninert gas, the pressure can be increased. Conversely, by closing thevents connected to an inert gas and opening the vents connected to avacuum the pressure can be decreased.

The vents of deposition chamber 130 can be similarly arranged withrespect to gas sources. For instance, each vent can be connected to anindependent gas source. Alternatively, two or more vents can beconnected to a common gas source. In this latter embodiment, each ventcan be independently controlled by an independently controlled valve.Alternatively, two or more vents of deposition chamber 130 can beconnected to a source by way of a common, independently controlledvalve. For example, all upper vents can be connected to a first gassource by way of a first common, independently operated valve, and allbottom vents can be connected to a second gas source by way of a secondcommon, independent operated valve. The bottom and upper vents may alsoall be connected to a common gas source with each group of ventsoperated by one or more independently controlled valves.

As an additional means to control the temperature inside depositionchamber 130, a means for controlling the temperature of the gas insidechamber 130 can be implemented. For example, as illustrated in FIG. 3 ,deposition chamber 130 may be equipped with a recirculation system 200that includes a fan 220 and optionally a heat exchanger 230. Fan 220 canbe used to intake the gas inside deposition chamber 130 and force it topass through heat exchanger 230. Heat exchanger 230 can either cool orheat the gas passing through it as desired. In an exemplary embodiment,heat exchanger 230 cools the gas passing through it. After passingthrough heat exchanger 230, the cooled gas is directed back intodeposition chamber 130 by way of pipes and vent system 240. The inletvents can be located at the ceiling of chamber 130. Alternatively, thevents can be located on the any one or more of chamber walls of chamber130. Alternatively, the inlet vents can be located at the floor ofchamber 130. In exemplary embodiments, the inlet vents can be located inmore than one location of the ceiling, chamber walls and floor ofdeposition chamber 130. The flow rate through recirculation system 200can be controlled with fan 220. In exemplary embodiments, fan 220 has acapacity ranging from 3000 to 6000 Sm³/hr. In an exemplary embodiment,fan 220 has a capacity of 4500 Sm³/hr. The air flow can be monitored andcontrolled so as to achieve desired conditions within the chamber. Thefans can be selected (such as to have a desired speed (rpm) and air flow(Sm³/hr.) and can be positioned so that the operation of the fanminimizes the introduction of any atmospheric turbulence inside thechamber due to the operation of the fans. In some application, the fanscan be turned off during deposition.

The recirculation system 200 can be operated independently of any otherventilation system of chamber 130. Controls for recirculation apparatus200 can be manual, automated or a combination thereof. In exemplaryembodiments, the control system acting on chamber 130 can also controlrecirculation system 200. Alternatively, recirculation system 200 canhave its own independent control system. In exemplary embodiments,recirculation system 200 can be operated during solid free formfabrication to modulate or better control the temperature of depositionchamber 130 during operation. For example, recirculation system 200 canbe used to cool the atmosphere inside deposition chamber 130 duringplasma transferred arc free form fabrication. Cooling the depositionchamber 130 during fabrication has the benefit of preventing overheatingof the deposition chamber 130. It can also prevent overheating of theequipment found in deposition chamber 130. It can further preventoverheating of chamber system 100 overall or at least of adjacentchambers.

As shown in FIG. 1 , in exemplary embodiments, deposition chamber 130 ispreferably equipped with at least one window 135. More than one windowcan be formed. The window allows an operator to monitor the solid freeform fabrication. The window also allows an operator to monitor theequipment found inside deposition chamber 130. One or more windows 135can form any portion of the chamber wall where they are provided. Forexample, a window 135 may occupy the full chamber wall. Alternatively,window 135 may take about three quarter of the chamber wall.Alternatively, window 135 may occupy about half the chamber wall.Alternatively, window 135 may occupy about a quarter of the chamberwall.

As discussed earlier, viewing portals, such as windows, can be made ofany suitable transparent material. Examples of transparent materialsinclude glass, acrylic material or thermoplastic polymers. In exemplaryembodiments, the viewing portal can be made of an acrylic material, suchas poly(methyl methacrylate). Alternatively, the viewing portal can be aglass. In exemplary embodiments, the viewing portal is made ofsoda-lime-silicate glass. The glass can be coated with one or moretransparent metal oxide layers that can reflect selected wavelengths ofelectromagnetic radiation. In some embodiments, the glass can reflectinfrared electromagnetic radiation. In some embodiments, the glass canreflect ultraviolet electromagnetic radiation. The glass can be presentin a single layer, or a plurality of layers of glass can be used. Insome embodiments, at least two glass layers are present, separated by aspace. The space between the two layers of glass can be filled with aninert gas. In some embodiments, the space between the two layers ofglass is filled with argon. This configuration can block up to about 85%ultraviolet radiation from being transmitted through the window. In someembodiments, at least two glass layers are present, and an interlayer ofpolymer film present between the two glass layers, forming a laminatedglass. The polymer film can be of any polymeric material, such aspolyvinylbutyral (PVB), ethylene vinyl acetate (EVA). The laminatedglass can block nearly 100% ultraviolet radiation from being transmittedthrough the window.

Alternatively, the viewing portal can be made of a thermoplasticpolymer. For example, the viewing portal may be made of a polycarbonate,acrylic or polyethylene terephthalate. The thermoplastic can be presentas a single layer, or two or more sheets can be fabricated to include aspace between the sheets, which optionally can be filled with argon, ora laminated plastic viewing portal can be prepared by including aninterlayer of polymer film between two sheets of thermoplastic polymer.The material used for the one or more viewing portals of one chamber canbe the same or different from the material used for the one or moreviewing portal of any other chamber. Also, different viewing portals ofone chamber can be made of the same or different materials.

Also, a viewing portal of deposition chamber 130 may further be equippedwith one or more viewing screens if needed. For example, in embodimentsin which plasma transferred arc is used for the solid free formfabrication, it is not possible or it can be difficult to monitor thearc with the naked eye. In fact, attempting to watch the process withthe naked eye may result in injury to the eye because of theelectromagnetic radiation emitted by the arc. Accordingly, a viewingscreen such as a filter lenses with a shade number that provides theappropriate level of protection can be provided at a desired location onthe one or more windows 135. In exemplary embodiments the filter lenseswith appropriate shade number is provided over the whole window 135. Inalternative examples, the filter lenses with appropriate shade numbercan be provided only at one or more discrete locations on window 135 asdesired. Also, different shade numbers can be provided at differentlocations of window 135 whether a single filter lenses is used over thewhole window 135 or if multiple filter lenses are provided at differentdiscrete locations. In exemplary embodiments the shading number can varybetween 5 and 15. In exemplary embodiments, the shading number at one ormore locations can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15.

The filter lenses can be of any appropriate material. Examples ofmaterials include glass, acrylic polymers and thermoplastic polymers. Inexemplary embodiments, the filter lenses can be made of an acrylicmaterial, such as poly(methyl methacrylate). Alternatively, filterlenses can be a glass. In exemplary embodiments, the filter lens is madeof soda-lime-silicate glass. In alternative embodiments the filterlenses can be made of polycarbonate. The filter lenses can be affixeddirectly on one or more window 135. Alternatively, filter lenses can beused to form one or more window 135. In alternative embodiments filterlenses may be integrated into one or more window 135. In exemplaryembodiments filter lenses can be free standing and positioned in frontof window 135. In exemplary embodiments, no filter lenses are providedon one or more window 135.

As discussed earlier, deposition chamber 130, like any of the otherchambers, may also be equipped with one or more cameras to monitor thechamber 130. One or more cameras inside deposition chamber 130 may alsobe used to monitor the fabrication process. The video recorded by thevideo cameras can be recorded. The video can also be streamed live to amonitor. The monitor can be located outside chamber 130. The monitor canbe located proximate to chamber 130. The monitor can be in a locationremote to chamber 130. Deposition chamber 130 may also be equipped withone or more illuminating fixtures as described earlier to provide lightinside chamber 130.

Deposition chamber 130 may include one or more doors. In exemplaryembodiments, deposition chamber 130 may include at least one door to aloading/unloading chamber. In an exemplary embodiment shown in FIG. 1 ,deposition chamber 130 is connected to two loading/unloading depositionchambers 110 and 120. As shown in FIG. 1 a wall can be shared betweendeposition chamber 130 and one or more loading/unloading chambers. Inthe illustrated embodiment, deposition chamber 130 can share the door112 and 122 with loading/unloading chambers 110 and 120. Doors 112 and122 have already been described above in conjunction withloading/unloading chambers 110 and 120. In an alternative embodiment,the passage between the deposition chamber and the loading/unloadingchambers can be sealed using more than one door. For example two doorsmay be used facing each other. Whether one door or multiple doors areused, the door can have the same structure and be designed to operate asdiscussed above already including their materials and optional one ormore sealing members. In embodiments in which the loading/unloadingchamber and deposition chamber each has its own door, each door can beindependently operated. Operation of the door of the loading/unloadingchamber can be controlled via the control system of theloading/unloading chamber. Operation of the door of the depositionchamber can be controlled via a control system for the depositionchamber. Alternatively, each door may have its own control system. Inyet an alternative embodiment, a control system can be used to operateboth doors.

A similar door arrangement as described above between the depositionchamber 130 and one or more loading/unloading chambers can also beprovided between deposition chamber 130 and service chamber 140.Alternative embodiments of a sealing door for service chamber 140 willbe described below.

Although not illustrated, deposition chamber 130 may also have a door tothe outside. The structure and elements of such door would be the sameas and designed to operate as the other doors described herein includingmaterial and optional use of one or more sealing members.

Any one or more of the doors or opening providing access to depositionchamber 130 can be fitted with one or more sensors able to detect whenthe given door is open or closed. The one or more sensors can beconnected to the control system controlling deposition apparatus 150. Inexemplary embodiments, if any one of the one or more sensors detectsthat any one or more of the doors accessing deposition chamber 130 isopened when it should be closed, or not properly sealed as it should be,they can communicate this by sending a signal to one or more controlsystems of chamber system 100. If during fabrication, in response tosignals received from the one or more sensors the one or more controlsystems can send a signal to deposition apparatus 150 to stop thefabrication process if in progress or to prevent it from starting. Theone or more sensors may also trigger an audible alarm, such as siren,warning voice and/or beeping noise, visual alarm, such as a flashinglight, blinking of light emitting elements inside one or more chambers,screen warnings on the one or more control systems, or combinationthereof.

SERVICE CHAMBER

Chamber system 100 may optionally include a service chamber 140. Servicechamber 140, as its name implies, can be used to service the depositionapparatus 150 without having to access deposition chamber 130 or withoutexposing chamber 130 to the outside atmosphere. Being able to maintainthe desired atmosphere, whether it be vacuum, inert gas, air, or otherinside chamber 130 can lead to an economic advantage and less downtime.This is because no energy, materials or time is required to fullyreplace the atmosphere in deposition chamber 130 every time maintenanceservice to the deposition apparatus 150 is necessary.

Service chamber 140 can be any desirable size. In exemplary embodiments,service chamber 140 is large enough to at least house depositionapparatus 150. In exemplary embodiments service chamber 140 is at leastabout 20% larger than the size of deposition apparatus 150.Alternatively, service chamber 140 is at least about 30%, 40%, 50%, 60%,70%, 80%, 90%, 100%, 125%, 150%, 175%, 200%, 300%, 400%, 500% largerthan the size of the deposition apparatus 150. Too large a size ofservice chamber 140 would require too much energy to evacuate and fillservice chamber 140 that would be costly. Service chamber 140 can beused to prevent having to spend the cost and time to evacuate and refilldeposition chamber 130, thus the size of service chamber 140 should bemuch smaller when compared to the size of deposition chamber 130. Inexemplary embodiments, the size of chamber 140 is as small as possiblethat still allows the housing of deposition apparatus 150 and sufficientroom to perform at least some maintenance without having to open servicechamber 140.

Service chamber 140 can be located anywhere in communication withdeposition chamber 130. In an exemplary embodiment, service chamber 140is located so as to be aligned with the middle of one end wall ofdeposition chamber 130. In an exemplary embodiment service chamber 140is aligned with the wire feed to deposition apparatus 150. By aligningservice chamber 140 with the wire feed to deposition apparatus 150, itis possible to move deposition apparatus 150 in and out of servicechamber 140 without bending wire feed 160 or without requiring removalof wire feed 160. This provides the advantage of not affecting wire feed160 nor to waste time removing and resetting wire feed 160 every timemaintenance is done on deposition apparatus 150.

In exemplary embodiments, service chamber 140 allows for the passage ofwire feed 160 through an opening 142 located at the distal end ofservice chamber 140 from deposition chamber 130. The opening 142 can beprovided with means to prevent outside atmospheric gases from enteringservice chamber 140. Such means can be designed depending on theoperating conditions of chamber system 100. In exemplary embodiments inwhich deposition chamber 130 is maintained under vacuum, the means caninclude sealing means, such as one or more sealing gaskets or membranesthat allow the wire feed 160 to pass through while maintaining thevacuum conditions. In exemplary embodiments in which deposition chamber130 is operated in an inert gas atmosphere, opening 142 can be equippedwith an inert gas blower. The gas blower can continuously blow inert gasout the opening 142 thus helping to prevent influx of outsideatmospheric gases. The blower can be any suitable blower and the amountof inert gas blown can be anywhere in an appropriate range that can helpprevent the influx of outside atmospheric gases. In exemplaryembodiments, the blower can blow at a flow rate of about 10 L/min. Inalternative embodiments, the blower can blow at a flow rate higher than10 L/min, for example 11 L/min, 13 L/min, 15 L/min, 20 L/min. Inexemplary embodiments, the blower can blow at any flow rate that createsa pressure that is higher than the pressure outside the chamber so as toprevent any gasses from entering the chamber.

Service chamber 140 can also be equipped with appropriate means forconducting maintenance on the deposition apparatus 150. For example, asillustrated in FIG. 1 , service chamber 140 can be equipped with a setof gloves 143 that allow an operator to work on the deposition apparatus150 without opening service chamber 140. Thus, service can be providedwithout subjecting the service chamber 140 to atmospheric communicationof the service chamber 140 to the exterior ambient environment. The setof gloves 143 allows service to be performed without opening the doorsof the service chamber 140.

Service chamber 140 can also be equipped with one or more windows 146.Window 146 can allow an operator to view the deposition apparatus 150without having to open service chamber 140. For example, an operator mayuse one or more window 146 to view deposition apparatus 150 while usinggloves 143.

Service chamber 140 may also be equipped with an access portal 147. Theportal may be integrated in the one or more windows 146. Alternatively,portal 147 can be provided separately from the one or more windows 146.Portal 147 can be designed to allow direct access to the depositionapparatus 150 so as to perform maintenance on deposition apparatus 150.For example, portal 147 may be used to replace parts on depositionapparatus 150. Portal 147 can be designed to allow for removal orinstallation of deposition apparatus 150. Like the previously discusseddoors, portal 147 can be design to swing open or slide. Portal 147 canalso comprise two panels that swing open. Portal 147 can be designed toform a gas impermeable seal when closed. The seal can be achieved usingone or more seal members as described earlier for the use with doors.One or more pressure mechanisms, such as hinges and/or springs, may alsobe used to put pressure on portal 147 when closed so as to improve theseal. The pressure can be removed when portal 147 is opened. Portal 147can also include a sensor that is able to detect when the portal 147 isopen or closed. The sensor can be connected to the control systemcontrolling deposition apparatus 150. In exemplary embodiments, if thesensor of portal 147 detects that portal 147 is opened duringfabrication, the control system can send a signal to stop thefabrication process.

Deposition apparatus 150 can be transferred from deposition chamber 130to service chamber 140 via a track system as described earlier withrespect to the motion apparatus provided for the deposition apparatus150 while inside deposition chamber 130. In exemplary embodiments, atrack system on the ceiling of service chamber 140 is provided.Alternatively the track can be provided on a chamber wall or the bottomof service chamber 140. The track inside chamber 140 can be an extensionof the track provided in deposition chamber 130 to which depositionapparatus 150 is connected while in deposition chamber 130.Alternatively, the track in chamber 140 can be a separate track that isable to engage deposition apparatus 150 when it enters service chamber140. Deposition apparatus 150 can be pushed or pulled on the trackinside service chamber 140 by the same motors, gears, wheels, pulleysystems, and conveyors provided inside or outside deposition chamber130. Alternatively, a motors, gears, wheels, pulley systems, andconveyors can be provided on deposition apparatus 150. Alternatively,separate motors, gears, wheels, pulley systems, and conveyors can beprovided inside or outside service chamber 140. Alternatively, some ofthe motors, gears, wheels, pulley systems, and conveyors can be providedinside or outside service chamber 140 and some are provided ondeposition apparatus 150.

Service chamber 140 can be in communication with deposition chamber 130through opening 141. Opening 141 should preferably be sized so as toallow at least the deposition apparatus 150 to pass through. Opening 141can be sealed from deposition chamber 130 using one or more doors asdescribed earlier between deposition chamber 130 and loading/unloadingchambers 110 and 120. The same type of door structure, materials, designand controls can be used here. In an alternative embodiment, instead ofplacing a door at opening 141, a door 144 with optional one or moresealing members 145 can be affixed onto deposition apparatus 150 at itsdistal end from service apparatus 140. In such exemplary embodiments, asshown in FIG. 2 , door 144 may be arranged such that when the depositionapparatus 150 is transferred to service chamber 140, door 144 andoptional one or more sealing members 145 seal opening 141. Thus, opening141 is sealed by door 144 and one or more sealing members 145automatically by transferring deposition chamber 150 into servicechamber 140. An advantage of the illustrated embodiment of FIGS. 1 and 2, is that the ability of sealing opening 141 without having to worryabout bending or having to remove wire feed 160. As illustrated in FIG.1 , this arrangement also provides that the service chamber 140 is incommunication with deposition chamber 130 every time the depositionapparatus 150 is located inside deposition chamber 130.

Like the other chambers, service chamber 140 can also be provided withits own independent ventilation system that allows service chamber 140to be under vacuum, in an inert gas or other gas atmosphere or in air.The same vents arrangement can be used as described above especially ifthe inert gas used is heavier than air, for example argon orargon-helium mixture. In exemplary embodiments, one or more vents usedto introduce and/or evacuate a heavier gas or gas mixture are providedat a bottom portion of service chamber 140 while vents used to introduceand/or evacuate a lighter gas or gas mixture, for example air, areprovided at an upper portion of service chamber 140.

Service chamber 140 can also be provided with its own independenttemperature and pressure monitoring and control devices similar to thosedescribed for all other chambers. All doors, portals and openings ofservice chamber 140 can also be equipped with one or more sensors in amanner similar to the doors and openings in loading/unloading chambers110 and 120 and deposition chamber 130 to detect if a door or opening isnot properly sealed when it should be and to communicate that to one ormore control systems of chamber system 100 which can then set off avisual and/or audible alarm, and which can stop or prevent from startingthe solid free form fabrication. With respect to opening 142, one ormore sensors can be used to monitor that the gas blower or other meansto prevent outside atmospheric gases from entering service chamber 140are properly functioning.

The following exemplary explanations are included for illustrativepurposes only and is not intended to limit the scope of the embodimentsprovided herein.

USE OF LOADING/UNLOADING CHAMBERS

In an exemplary embodiment, deposition chamber 130 is prepared for solidfree form manufacturing by setting the desired atmosphere. For example,air is evacuated from deposition chamber 130 and replaced by an inertgas or inert gas mixture such as argon or argon-helium mixture. The airis evacuated from deposition chamber 130 using a vacuum pump connectedto a first set of one or more vents at the upper portion of depositionchamber 130. After activation of the vacuum pump, a control system isused to operate the valves connecting the vacuum to the first set ofvents of deposition system 130. The control system may be manual,computerized or a combination thereof. The first set of vents can belocated for example on the ceiling and/or at an upper portion of thechamber walls. By applying the vacuum, air is drawn out of depositionchamber 130 from the first set of vents located at the upper portion ofdeposition chamber 130. Simultaneous to the evacuation of air fromdeposition chamber 130, a control system, that can be the same ordifferent from the control system operating the valves connecting thevacuum to the ventilation system of deposition chamber 130, is used tointroduce an inert gas or inert gas mixture into deposition chamber 130.This latter control system may also be manual, computerized or acombination of both. The inert gas or inert gas mixture is introducedinto deposition chamber 130 by way of a second set of one or more ventslocated at the bottom portion of deposition chamber 130, i.e. the floorand/or a bottom portion of the chamber walls. The inert gas or inert gasmixture includes at least one gas that is heavier than air. In thismanner as the air is evacuated from the top of deposition chamber 130,inert gas or inert gas mixture is introduce from the bottom. The supplyof inert gas or inert gas mixture can be provided by opening valvesconnected to a second set of vents of deposition chamber 130 that areseparate from the first set of vents.

The supply of inert gas or inert gas mixture and evacuation of air indeposition chamber 130 is conducted such that the formation of deadpockets of air is minimized or eliminated. This process continues for asufficient period of time until an oxygen detector present in depositionchamber 130 detects that the presence of oxygen is below 50 ppm. Duringthis process, the pressure of deposition chamber is monitored using apressure gauged and it is adjusted to be in the range of from about 3 toabout 6 millibar above atmospheric pressure.

During the above process deposition chamber 130 is sealed off from anyloading/unloading chamber and the outside atmosphere by one or moredoors.

A holding substrate is loaded into a loading/unloading chamber 110 byopening door 111 of the loading/unloading chamber 100 that providesaccess to an operator and positioning the holding substrate over theconveyor 113 located inside loading/unloading chamber 110. Once theholding substrate is loaded into the loading/unloading chamber 110, theone or more access doors 111 can be closed so as to provide a gasimpermeable seal. The atmosphere of the loading/unloading chamber isthen replaced with one of inert gas or inert gas mixture. The process issimilar to that described for the deposition chamber 130. A vacuum pumpis connected to first set of one or more vents at the upper portion ofthe loading/unloading chamber to evacuate air from the chamber while aheavier than air inert gas or gas mixture is introduced from a secondset of one or more vents located at the bottom of the loading/unloadingchamber. The atmosphere of the loading/unloading chamber is made to besubstantially the same as that of the deposition chamber measuring theconditions using the loading/unloading chamber's independent oxygendetector and pressure gauge.

Once the atmosphere of the loading/unloading chamber 110 issubstantially similar to that of the deposition chamber 130, the one ormore doors 112 sealing the loading/unloading chamber 110 from depositionchamber 130 are opened. The conveyor 113 inside loading/unloadingchamber 110 is then operated to transfer the holding substrate onto theactuator 131 located inside deposition chamber 130 and positioned inproximity of the one or more doors 112 ready to receive the firstholding substrate.

Once the transfer is accomplished, actuator 131 moves into the startingposition for solid free form fabrication and the one or more doors 112are closed. The solid free form fabrication process then commencesinside deposition chamber 130. During fabrication, the inert atmosphereinside loading/unloading chamber 110 is maintained. During fabrication,recirculation system 200 of deposition chamber 130 can also be activatedto chill the inert gas or gas mixture during free form fabrication toprevent overheating of deposition chamber 130 and/or of the equipmentlocated inside deposition chamber 130.

Meanwhile a second holding substrate is loaded into loading/unloadingchamber 120 by opening access door 121 and position the second holdingsubstrate on conveyor 123. Access door 121 is then closed to provide agas impermeable seal and the atmosphere inside is replaced with an inertatmosphere as described above for loading/unloading chamber 110.

Once the solid free form fabrication is completed using the firstholding substrate so as to produce a first workpiece, the fabricationprocess stops and actuator 131 now holding the first workpiece movesback to a position proximate the one or more doors 112. The one or moredoors 112 are opened again and the conveyor 113 retrieves the firstworkpiece from actuator 131. After the first workpiece is placed back onconveyor 113, the one or more doors 112 are sealed closed again.

After the first workpiece has been transferred to loading/unloadingchamber 110 and the one or more doors 112 are closed, actuator 131 ismoved to a position proximate the one or more doors 122. The one or moredoors 122 then open and conveyor 123 transfers the second holdingsubstrate onto actuator 131. Once the transfer has occurred, the one ormore doors 122 seal closed, actuator 131 moves back in the startingposition for solid free form fabrication and solid free form fabricationbegins on the second holding substrate. During this fabrication process,the inert atmosphere in loading/unloading chamber 120 is maintained.

Meanwhile, the atmosphere in loading/unloading chamber 110 is replacedwith air by applying a vacuum to the bottom set of one or more vents ofloading/unloading chamber 110 and by introducing air through the upperset of one or more vents of loading/unloading chamber 110. Once theatmosphere in loading/unloading chamber 110 has been replaced withambient air at atmospheric pressure, the one or more doors 111 areopened and the first workpiece is retrieved. In this manner, theoperator retrieving the first workpiece is not exposed to the inert gasor inert gas mixture atmosphere that may be harmful to the operator.After unloading the first workpiece, the operator may load a thirdholding substrate onto conveyor 113. The one or more doors 111 are thenclosed and the atmosphere inside loading/unloading chamber 110 againreplaced with inert atmosphere as done previously.

Once solid free form fabrication is completed on the second holdingsubstrate to form a second workpiece, actuator 131 holding the secondworkpiece is moved back to a position proximate the one or more doors122, which are then opened, and the conveyor 123 retrieves the secondworkpiece transferring it back into loading/unloading chamber 120 in amanner similar to what was done for transferring the first workpieceonto conveyor 113. The one or more doors 122 are then closed andactuator 131 is moved to be in a position proximate to one or more doors112 ready to receive the third holding substrate in the same manner itreceived the first holding substrate.

Meanwhile, the atmosphere in loading/unloading chamber 120 is replacedwith air in a similar manner as was done for loading/unloading chamber110. The second workpiece is then retrieved from loading/unloadingchamber 120 by accessing it via the one or more doors 121. A fourthholding substrate is then loaded onto conveyor 123.

The process above is repeated for as many workpieces that are to beproduced. In the above manner, it is possible to expedite productionprocess by not having to expend time waiting for the atmosphere inloading/unloading chamber to be replaced to transfer the holdingsubstrate onto the actuator 131 as that process will have already beendone by the time actuator 131 is ready to receive a new holdingsubstrate, while also providing a way to quickly unload the previouslyformed workpiece.

During the above process, one or more sensors can be used to monitor thedoors giving access to the deposition chamber during solid free formfabrication. If a door is not properly sealed shut or if a door isopened during the fabrication, the one or more sensors would send asignal reflecting that to the control system that controls thedeposition apparatus and the solid free form fabrication process iseither prevented from starting or if stopped if already started. In sodoing, the solid free form fabrication is not exposed to an atmosphereother than what is intended.

USE OF SERVICE CHAMBER

In an exemplary embodiment, chamber system 100 may include servicechamber 140 connected to deposition chamber 130. This may be inconjunction with also having one or more loading/unloading chambers alsoconnected to deposition chamber 130. The operation of one or moreloading/unloading chambers would be as described in the first exampleindependent of whether a service chamber 140 is also used.

In an embodiment, the deposition apparatus 150 can be moved into servicechamber 140. One or more doors 144 with one or more sealing members 145can be provided at one end of deposition apparatus 150 so that asdeposition apparatus enters service chamber 140, one or more doors 144with one or more sealing members 145 are brought closer to opening 141.With this configuration, when deposition apparatus 150 is completelyinside service chamber 140, one or more doors 144 and one or moresealing members 145 close opening 141 to create a gas impermeable sealbetween service chamber 140 and deposition chamber 130.

After deposition apparatus 150 is moved into service chamber 140, theatmosphere in deposition chamber 130 may be independently modified asdesired in a similar manner as described in Example 1. If the atmospherein deposition chamber 130 is already as desired, then deposition chamber130 can simply be maintained.

The atmosphere in service chamber 140 can also be independentlymodified, if desired, once the deposition apparatus 150 is placedtherein and opening 141 has been sealed. Replacement or adjustment ofthe atmosphere in service chamber 140 can be accomplished is mannersimilarly described above for the deposition chamber and/or theloading/unloading chambers. In other words, vents are located at theupper and lower portions of service chamber 140. Air or other light gasatmosphere may be introduced or evacuated from chamber 140 using one ormore vents at the upper portion of service chamber 140. Likewise, heavygas atmosphere may be introduced or removed using one or more vents atthe bottom portion of service chamber 140. If service chamber 140 is tobe used under vacuum conditions, a vacuum can also be applied to allupper and bottom vents simultaneously. Such can equally be done to anyother chamber. Also, if vacuum conditions are desired, any subset ofupper and bottom vents or combination of upper and bottom vents can beused independent of whether the atmosphere being evacuated. This alsoapplies to the other chambers described herein, including depositionchamber 130 and loading/unloading chambers 110 and 120.

In an embodiment in which the service chamber 140 was already filledwith an inert atmosphere, it may be desirable to simply maintain theatmosphere even after the deposition apparatus 150 has been transferredinto chamber 140. If deposition apparatus 150 is in need of maintenance,an operator may perform such maintenance using gloves 143. The operatormay view deposition apparatus 150 while performing the maintenance bylooking through window 146.

If the required maintenance is not easily accomplished using gloves 143or if the operator simply decides not to use gloves 143 to perform themaintenance, then the deposition apparatus can be accessed via portal147. To avoid exposing the operator to potentially harmful gases, or ifthe service chamber 140 is under vacuum conditions when the depositionapparatus 150 is transferred therein, then the atmosphere inside servicechamber 140 can be replaced with air at atmospheric pressure prior toopening portal 147.

Once maintenance is complete, portal 147 is closed (if it had beenopened) and the atmospheric conditions of service chamber 140 ismodified, if necessary, to be similar to those of deposition chamber130. Once acceptable atmospheric conditions are achieved in servicechamber 140, the deposition apparatus 150 is returned to depositionchamber 130. In this manner, the atmosphere in deposition chamber 130 isnot substantially affected by unsealing opening 141.

As deposition apparatus 150 moves in and out of service chamber 140,wire feed 160 remains straight. As deposition apparatus 150 moves towardopening 141, and as it enters service chamber 140, a portion of wirefeed 160 exits service chamber 140 by way of opening 142. As thedeposition apparatus 150 enters deposition chamber 130, and moves deeperinto deposition chamber 130, wire feed 160 enters service chamber 140 byway of opening 142. Additional wire feed 160 also enters service chamber140 by way of opening 142 during solid free form fabrication as wirefeed is used for the solid free form fabrication.

As described in Example 1, any portal or other door or opening ofservice chamber 140 can be monitored by one or more sensors. If one ormore sensors detect that portal 147 or other door or portal, with theexception of opening 141 and opening 142, is not sealed as desired, orif it senses inflow of outside atmosphere from opening 142, a signal canbe sent to the control system for the deposition apparatus in depositionchamber 130 to either prevent the start of a solid free form fabricationor to stop an on-going solid free form fabrication process. This avoidsexposing the workpiece to an undesired atmosphere during manufacturing.Also, an audible alarm, visual alarm or combination thereof can be setoff when one or more sensors signal a leak, lack of seal or opening inservice chamber 140.

Likewise, one or more sensors may be used to monitor the sealing ofopening 141 when deposition apparatus 150 is in service chamber 140. Anaudible alarm, visual alarm or combination thereof can be set off if theone or more sensors detect that opening 141 is not properly sealed sothat an operator is alerted that modifying the atmosphere in servicechamber 140 can affect the atmosphere of deposition chamber 130.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the scope of the invention. Thus, it is intended that thepresent invention cover the modifications and variations of thisinvention provided they come within the scope of the appended claims andtheir equivalents.

What is claimed is:
 1. A chamber system for solid free form fabricationcomprising: one or more independently controlled loading/unloadingchambers; an independently controlled deposition chamber, the depositionchamber including a deposition apparatus comprising a heat source; oneor more doors connecting the deposition chamber with each of one or moreloading/unloading chambers; and an independently controlled servicechamber connected to the deposition chamber, the service chamber sizedto house the deposition apparatus, and arranged such that the depositionapparatus can move in and out of the service chamber without removing awire feed to the deposition apparatus.
 2. The chamber system of claim 1,wherein each of the one or more loading/unloading chambers furthercomprises: one or more doors providing access to the loading/unloadingchamber; a conveyor located inside the loading/unloading chamber; andone or more vents.
 3. The chamber system of claim 2, eachloading/unloading chamber comprising a vent located at an upper portionof the loading/unloading chamber and a vent located at a bottom portionof the loading/unloading chamber; the vent located at the upper portionbeing operatively connected to a vacuum pump and to an air supply; andthe vent located at the bottom portion being operatively connected to avacuum pump and to a source of inert gas or inert gas mixture.
 4. Thechamber system of claim 1, further comprising two loading/unloadingchambers with a wall in common between them, and wherein eachloading/unloading chamber also has a wall in common with the depositionchamber.
 5. The chamber system of claim 1, the deposition chamberfurther comprising one or more vents located at an upper portion of thedeposition chamber and one or more vents located at a bottom portion ofthe deposition chamber; the one or more vents located at the upperportion being operatively connected to a vacuum pump and to an airsupply; and the one or more vents located at the bottom portion beingoperatively connected to a vacuum pump and to a source of inert gas orinert gas mixture.
 6. The chamber system of claim 1, the depositionchamber further comprising one or more viewing portals.
 7. The chambersystem of claim 1, the deposition chamber further comprising arecirculation system comprising a fan and a heat exchanger.
 8. Thechamber system of claim 1, the service chamber further comprising one ormore vents at an upper portion of the service chamber and one or morevents at a bottom portion of the service chamber; the one or more ventslocated at the upper portion being operatively connected to a vacuumpump and to an air supply; the one or more vents located at the bottomportion being operatively connected to a vacuum pump and to a source ofinert gas or inert gas mixture.
 9. The chamber system of claim 1, theservice chamber further comprising an access portal.
 10. The chambersystem of claim 1, the service chamber further comprising a set ofgloves.
 11. The chamber system of claim 1, wherein the depositionapparatus is configured to move relative to a holding substrate that iskept at a fixed location.
 12. The chamber system of claim 1, furthercomprising an actuator for holding a base material, wherein the actuatorand deposition apparatus are configured to generate a displacementrelative to each other by: a motion of the deposition apparatus whilethe actuator remains at a fixed position, a motion of the actuator whilethe deposition apparatus remains at a fixed position, or a motion of thedeposition apparatus and of the actuator.
 13. A method of operating achamber system for solid free form fabrication comprising: independentlyreplacing the atmosphere in a deposition chamber of the chamber systemwith an inert atmosphere; transferring a first holding substrate to thedeposition chamber while maintaining the inert atmosphere in thedeposition chamber; performing solid free form fabrication using adeposition apparatus comprising a heat source within the depositionchamber to form a first workpiece; and transferring the first workpieceout of the deposition chamber while maintaining the inert atmosphere inthe deposition chamber, wherein the chamber system comprises thedeposition chamber and a service chamber sized to house the depositionapparatus and being arranged such that the deposition apparatus moves inand out of the service chamber without requiring removal of a wire feedto the deposition apparatus.
 14. The method of claim 13, wherein thechamber system further comprises one or more loading/unloading chambers,the one or more loading/unloading chambers and the service chamber beingin communication with the deposition chamber through one or moreindependent openings, further comprising controlling each of thedeposition chamber, one or more loading/unloading chambers, and theservice chamber independently.
 15. The method of claim 14, wherein thechamber system further comprises one or more doors to seal the one ormore independent openings, further comprising monitoring the one or moredoors at each of the deposition chamber, one or more loading/unloadingchambers, and the service chamber using one or more sensors.
 16. Themethod of claim 15, further comprising stopping the solid free formfabrication if one or more sensors detects that at least one of the oneor more doors is not properly sealed closed.
 17. The method of claim 13,wherein the chamber system further comprises one or moreloading/unloading chambers, the one or more loading/unloading chambersand the service chamber being in communication with the depositionchamber through one or more independent openings, further comprising:loading a first holding substrate on a conveyor located inside a firstloading/unloading chamber; replacing the atmosphere in the firstloading/unloading chamber with the same inert atmosphere as in thedeposition chamber; and maintaining the atmosphere inside the firstloading/unloading chamber during transfer of the holding substrate tothe deposition chamber and during solid free form fabrication.
 18. Themethod of claim 17, further comprising: loading a second holdingsubstrate onto a conveyor of a second loading/unloading chamber whilemaintaining the inert atmosphere in the first loading/unloading chamber;replacing the atmosphere of the second loading/unloading chamber withthe same inert atmosphere as in the deposition chamber.
 19. The methodof claim 18, wherein transferring the first workpiece out of thedeposition chamber comprises: transferring the workpiece into the firstloading/unloading chamber while maintaining the inert atmosphere in thefirst loading/unloading chamber; sealing the first loading/unloadingchamber from the deposition chamber; replacing the inert atmosphere inthe first loading/unloading chamber with ambient air; and unloading theworkpiece from the loading/unloading chamber.
 20. The method of claim 19further comprising: after sealing the first loading/unloading chamberfrom the deposition chamber, transferring a second holding substratefrom a second loading/unloading chamber to the deposition chamber whilemaintaining the inert atmosphere in the deposition chamber.
 21. Themethod of claim 13, wherein performing solid free form fabrication usinga deposition apparatus comprises: moving the deposition apparatus whilethe holding substrate is at a fixed position, moving the holdingsubstrate while the deposition apparatus is at a fixed position, ormoving the deposition apparatus and the holding substrate.